I want to thank everyone here for being so supportive through Boomer's ordeal. I'm very grateful for all your sincerity and concern. You guys are awesome.
As Chris said, Boomer is fine

Not quite out of the woods yet, but the Doctor's positive comments about his check-up and treatment gives me confidence that the worst part is over. I apologize in advance if this is going to be a long post. Last night, when I was distraught perusing the internet, I hoped to find a thread that talked about concussion or trauma in birds from the time of the accident to the treatment. While every situation is different, I hope that someday, Boomer's thread becomes helpful to someone else in the future. If only to give them an idea of what to expect.
I honestly thought I was seeing Boomer's last minutes alive yesterday morning. It was the most horrible feeling. He hit the closet door with a loud thud. He fell on the carpet wings flapping. I walked up to him but he flew out of the room, back to his cage. His flight seemed labored. When he got to his cage, he was panting so hard. I asked him to step up, which he did. I put him back on my shoulder and foolishly took him back to the room to see where he hit the closet. This was my biggest mistake. Whilst on my shoulder, a plane flew above and it might have cast a shadow on the window. Boomer, perhaps still disoriented, freaked out and flew. He was flying all over the place, sometimes dragging across the carpet, wings uncoordinated, staggering. If I would have taken him somewhere dark, blanketed him, instead of taking him back the bright room, I could have avoided the whole freak out session. Birds who suffered a concussion become very photo-sensitive so it is best to take them somewhere dark and safe- I know that now but did not at the time.
Today, went to Avian and Exotic Animal Hospital in Hawthorne, CA. This clinic, and the doctor, is highly regarded in the area. He has plenty of achievements and an extensive experience treating birds. He had scores of positive, 5-star reviews from actual bird owners online. I felt we were in good hands. Boomer and I got to the vet's and waited about 20 minutes because they were running behind schedule. When it was our turn, they called me in this small room. I took Boomer in his carrier and set him down on a table. The doctor was this older gentleman, extremely nice and patient. He listened to me explain my long story. I told him about my concerns for internal bleeding, fractures and micro fractures, and brain inflammation. I emphasized that Boomer is acting like his old self. The only symptom remaining were the minor bruising on his forehead where he lost a few feathers from the impact and the tiny bruising on the skin of his right eye. He did not pay much attention to Boomer at this time, he was just listening to me and trying to reassure me which I needed badly. He said that birds, especially sun conures, are tough little guys. He has seen birds hit a window hard, fall down with their necks seemingly broken, head tilted, then get up after 30 minutes like it was nothing. BUT, he said, that is not to say there is nothing wrong with Boomer. He said blood could have formed internally in the sinuses. He said inflammation is also a concern but he has to perform a check-up to know for sure.
With that he said he would take Boomer in the backroom, that it was better I don't go in so that Boomer won't think I'm the bad guy. He was gone before I could even say another word. I heard a few screeches from Boomer so I asked the receptionist and a wandering technician if I could go in the backroom. They were apologetic but said I could not because it is company protocol. They said there were other animals back there that might get distressed by my presence. So I reluctantly just went back and waited in the small room that the doctor saw me in. I still feel they should have let me in with Booms.
The doctor came out with Boomer after 30-40 minutes. He said not to worry, Boomer was fine. He gave him an
injection of doxycycline/dex. This did 2 things. One, it was an antibiotic to make sure Boomer does not get any infection. It will last 7 days in his system. Two, it was an anti-inflammatory incase he had any swelling in the brain. He highly doubts the inflammation part. In fact, he said he was going to have me buy some oral anti-inflammatory (forgot the name) at first, but decided not to after the check-up because he really doesn't think Boomer needed it. He said that
IF Boomer had swelling in the brain, I would have seen symptoms right away such as ataxia, disorientation, weakness, lethargy, not being able to perch, etc.
After checking his poop from the morning (attached pic as promised ) and a fresh one he just made, he determined there was no internal bleeding. He added, after I asked him, that in cases of internal bleeding from concussions/trauma, poop will show blood only
IF the damage was in a specific part of the body. I forgot which, but it had something to do with a tract, somewhere in the lower abdominal area. He also said that if there was internal bleeding in this area, it would have been apparent in the poop almost immediately, not after a few days.
He did not see any signs of bleeding in the sinuses. He felt for injuries, but did not find any. He said he was going to be fine. He even added that Boomer was, and I quote "A very healthy bird with a strong heart, strong lungs and perfect weight." BUT he said, that's not a guarantee the bird is perfectly healthy. He said that traumatic events can cause certain dormant diseases to kick into gear. Which is why he took the liberty to perform a
Gram Stain and
Avian CBC to make sure he has no yeast infection or a carrier of psittacosis. I did not like that they did not ask me, but I did want to get these tests done so I did not fuss about it. They should have still asked me though.
I also asked him about the possibility of Boomer turning phobic because of his accident. He was never phased by loud planes before, well maybe in the very beginning, but he got over it because planes passed by our building all the time. Well yesterday and today, I've noticed him twice now fly to me or to his cage, when a plane passed by. Sometimes he'd have no reaction. I wondered if he connected his accident to the plane passing by right at that moment. The doctor said that it was possible that he might develop a phobia. To counter it, I must calm him when I hear a plane coming. He said that birds are smart and figure out sooner or later, that the planes pose no threat.
So that's it. Sorry for the long, long response. Long story short: Boomer is going to be just fine but were not quite out of the woods yet. I will be monitoring him just in case and to make sure he has no adverse reaction to the doxycycline/dex. When I have a significant update, I'll resurrect the thread. When I am sure he is going to be A-OKAY, I will also resurrect the thread. This way, future paranoid parronts will know that this had a (hopefully) happy ending. I just want to say again, thank you to everyone for the kind comments and the warm thoughts. It really, really, really made a difference in a horrible event such as this. Boomer thanks you all!
(Picture of morning poop as promised. Doctor gave it the ok. Gross I know, but I know you guys are used to this haha)