HELP! sick silver-tip!

I have a pair of silver-tip sharks, and Jeckle is sick! He appears to be a bit bloated. However, I don't know if he's over eaten, considering I've never even seen these fish eat. They were transfered to my larger tank from a friend's 20g to save their lives. Little did I know one of them would die in my hands. I took him out of the tank and placed him into a tupa-ware were he has his own airator and food. He can't keep himself balanced, always swimming in circles, not in circles left or right, but up and down. When he rests, he's either almost belly-up or heads-up... I would appreciate help in either telling me what his condition is, or whatever I can do to help revive and succesfully heal him! Any hints or suggestions? Even some home-remedies would help!