My vet can make giving oral meds look so easy, but alas.. I cannot do it with nearly as much grace as he can...
The way he gives it (and is the professional way) is to put your hand backwards of the beak by the head, and slowly drip the meds in the very corner of the beak up near where it joins the head. Even with the beak closed, there should be a little space for liquid to get in (the beak doesn't shut air tight lol). I have found that unless you are a professional at giving meds, this technique is only easy if you have a bird who doesn't fight it. I admittedly have not mastered it in a bird who tries to wildly move their head, beak, and tongue around as Raven does.
So, I find that with Raven who I am currently giving antifungal meds to twice a day for a couple more months yet, is a bit easier to handle if I go about it by covering his eyes. "Burrito" your bird in a towel (the kind of burrito with an open top lol).. and gently hold the head secure. If you have a bird who still tends to try to move their head around, shield the eyes with the towel. Not being able to see the syringe coming will calm him down significantly. This trick is the only thing I've found that will make it a tiny bit easier to place the full dose of liquid into a moving target. I'm getting better at it... Good luck. Hope your little one has a speedy recovery.
*Another thing... Once the meds are inside the mouth, make sure they move the mouth and tongue a little before releasing them from the towel to show that they're swallowing it. Otherwise, I found that birds I've had to medicate (including Raven) will try to store the liquid in the bottom section of the beak, and then shake it all out of their mouth once they're out of the towel. Drip the meds slowly and making sure they swallow each drop before giving the next.