Can't advise on what we don't even see... post pics please. May not even be "scale rot"- do tell us about his enclosure. (size, what substrate is used? -hi & low temps.- heat sources & how they are regulated?
humidity? & how are you reading his cage temps.?) Cannot help you much without more info...& even then, you might need a good experienced herp vet. We are here to educate & help, but cannot substitute
for your vet's assistance, if it's needed.