Well I would just keep an eye on him. With no mucus or labored breathing it doesn't sound like RI. It may just a a ball being a ball.
Get a tstat and I would suggest a temp gun. With the temp gun you can more accurately check surface temps. Amazon has them cheap.
After you get him all set up and know for sure everything is correct we can see if he takes prey. I would also suggest leaving him alone except for cleaning and checking for more signs or symptoms of an issue.
Mites can be a pain if you do not clean everything, everything, everything, did I say everything very thoroughly. Change all substrate and spray down and clean everything in, near, around, close to your snake, in its cage, or any place its been.