Quote Originally Posted by UrdnotWrex View Post
I initially thought it might be a burn but I can't see how that could be. I do use an UTH, but there is a lining underneath his substrate which wouldn't allow him to be in a position to be burned by it.
I'm guessing by this that you don't have a thermostat to keep the uth at the correct temperature
It looks like scale rot to me too and I'd be to the vets sooner than later for your snakes sake.