I'm back.
After talking with someone who's beend dealing with mice for 3 years, it doesn't look good.
It seems likely that he hurt himself on the wheel...probably doing the loop-de-loop, he fell off and got cought in the blades, and has hurt his back...he can barely walk on his hind legs, and when he does move, he drags himself along his belly.
He's a bit more active now, but the person told me not to get my hopes up.