I had to deal with scale rot as an early keeper, my lesser as a baby kept spilling his water bowl every night and it got to the point where he devolved it, new water bowl fixed that problem. I treated him at home with just neosporn and cleaning his cage every day until he shed twice, thats when the wounded didn't look open anymore. He still has a scar even into adulthood.

now with that said, he only had a 2 inch area that had it, your snake looks like most of the belly... i guess if you have no option, keep treating with neosporn and clean the cage every day or even more often than that. paper towel is cheap, keep changing it. If it gets any worse, you need to see a vet or give the snake to someone who has the funds to deal with it sorry to say.