Really Sick Fire Belly? What's wrong?

[uglycomicsinc]

I bought one of my fire bellied toads from Petsmart a little less than 2 years ago and there has never been any problems with him. However, a few days ago, I needed to rearrange the tank and needed to put him in a plastic container (with some water and hiding spots) for about 30 minutes. During this time, however, he managed to escape and landed on the floor (which was maybe about a 3ft drop.) I quickly scooped him up and put him back in the container. After cleaning and rearranging the tank I put him and his tank mates back in the tank. The other 2 are fine but the one has been acting very strangely ever since. He constantly wants to sit in the water, but doesn't seem to have enough energy to keep himself afloat. I don't notice any body abnormalities. He also seems extremely exhausted and whenever he jumps he seems to roll over onto his stomach and then lazily rolls himself over. I have tried to feed him but every time he sees me or the food he just runs away. When I finally manage to find him, he completely refuses to eat. I don't think he's eaten anything for more than a week. I have currently put him in quarantine in a 2.5 gallon container with a very shallow layer of water and some hiding spots. What is wrong with him? What can I do for him? Please help because I have never had any problems before in the 2 years that I have kept them.