Dehydration might be playing a role here as well. Small adult mice isn't nearly enough for her at that age if she's only getting one. Ball pythons don't drink a lot. They get most of their liquids from their prey. Try multiple mice or a rat the widest part of her body or even a hair larger. For humidity, I have one snake in a glass enclosure and I have a water bowl almost 1/3 the size of the tank to help . The humidity usually never drops below 50%.