Help! Skin falling off snake!?!?!?!

[corallee]

Okay, so i just rescued a Ball Python. Probably only 3-4 months old, lady had the snake for just about 6 months and she hadn't gotten him to eat in 4 months. when i got him he was EXTREMELY skinny and EXTREMELY dehydrated. i've had him 2 going on 3 weeks now. I have forced feed him twice, and he is hydrating well, almost no more loose skin(yay). I have been worried though, because he hasn't been pooping(two mice in, no poo out not good) Today, I had him in a nice warm soak(15-20 minutes) and then i was messaging his tummy because i could feel the poo in him. I got two very hard about dime sized uric acid clumps out of him plus a bunch of other oozy goozy pooy things came running out of him.

all of that i'm cool with and understand, but this leads me to my problem. His skinny on his back, where i was messaging his belly(but on his back) started pulling away from him. and it left a very white, translucent skin underneath. and this worrys me. Any insight? or suggestions?

ps: (THIS IS NOT SHED, I AM 100% CRETIN OF THAT)