Google images of burned snake bellies and see what you think. Your pics look like the start of a burn. Maybe it is in shed as well but the browning and the wrinkled center is not from a shed, not any shed that I have seen.

I know the paper towels you were using and those are really expensive for a snake substrate. But even with the quality and thickness they are not thick enough to protect from an unregulated uth. Plus like I said snakes can get under paper towels and newspaper with ease. Plenty of noobs will argue that they can not but I assure you they can.

Your snake still needs water. If your snake is truly in shed your still going to need the humidity or you are going to have even a larger problem. Hopefully it is in a shed and will shed much of the problem off well to start the healing. I would still change the paper towels daily until we know for sure what this is.

Do you have any other signs of shed? Foggy eyes, blue foggy skin, etc.