Hi. I am NOT a vet, but it looks to me like the urine probably came out clear but the color from the feces bled into the paper towel making it look light green. Those look like fairly normal poops from a bird on a seed diet. The vitamins could be making his poop a little runny, but if the vet prescribed them, you need to keep using them. It also may be he has had increased fluid intake, such as eating a moist fruit or food, taking a bath or even just drank a little more. There is endless information out there about how to get a parrot to try fruits and veg, all you have to do is find a method that works for your bird. It's actually a fairly common problem (improper diet), especially with older rehomes who have not been properly cared for. Our BFA came to us not eating fruit and veg, but he learned they aren't the devil in his dish

One thing I've found very helpful is giving him his fresh food FIRST (when he's really hungry) and AFTER he's dated a good amount, then he gets his other food. I also find he likes cooked grains a lot more than seeds, which are a lot healthier for him too. I am personally pretty anti-pellet because they are processed and I just don't think they are an appropriate dietary staple. We use the Volkmans feather glow line instead of seeds or pellets as his staple food, and there are 2 types of cooked food-
Volkman Seed Company Volkman Seed Company
He likes both, and it's SO much more nutrias than seed. IF you do try them, the poops will get runnier due to increased moisture (which is ok).
Here is another good thread on what is and isn't safe to feed your bird:
http://www.parrotforums.com/parrot-...afe-fresh-foods-toxic-food-lists-sprouts.html
My boy is a lot less excited about fruit and veg than he should be, so I give him extra by baking it into stuff. Amazons are kind of pigs, so sometimes giving them what looks like people food makes them more excited to eat it. Here are 2 of my easier birdie bread recipes and you can substitute in any fruit or veg you'd like:
http://www.parrotforums.com/parrot-...60-healthy-eating-home-made-single-birds.html
Also curious, but what kind of illness did he have and what was the medication? Antibiotics, while a life saver when dealing with infection, actually wipe out the healthy bacteria in the gut. This can cause diarrhea too, while on them and for a good time after. Most vets will suggest feeding (small amounts) of yogurt to the bird after the round of antibiotics to help repair the damage done to the natural gut flora. I would ask the vet if he suggests this for your bird. Most birds are fine to eat small amounts of dairy, but without knowing what was wrong with your bird or anything, I would check with the vet first. Best of luck.