He is a rescue and we have had him about a month now, I don't know what's going on and we really need help.
He didn't have this problem when we got him but constantly laid on his back and scratched his butt on the carpet (we thought it was cute) and now he's attacking his tail and right above his tail to the point he can't sit still and he starts shaking.
We have tried medicated shampoos and recently bought a open wound spray since he can't leave it alone.
RECENT UPDATE: at 4:36 this morning he had diarrhea (which never happens, he never poops in the house nor have we even seen him poop period, we always thought he was private about it) he ran to our room and seemed upset that he would be in trouble or telling us he needed to go out... I took him out and as soon as we hit the grass in the lawn he tried pooping but yelped and then ran away back to the porch.