With regards to whatever is going on with the belly, you have a couple of options:

(1) Take her to a vet.

(2) Throw out all the substrate and replace with paper towels. Stop misting the enclosure. The idea is to provide as sterile an environment as possible. If you need to raise the humidity, do so by using a larger water dish and placing it under or on top of the heat source or by using a humid hide. Until her belly issue is resolved, quit with the spritzing and get rid of the bark.

You have apparently decided that humidity is more important than proper temps (as is evidence by the fact that you have foregone the correct heat gradient and ambients in favor for humidity - I strongly suggest you rethink this approach. It is flawed. It will most likely lead to a lot more serious health issues than she currently has.

To recap:

Get her temps correct.

Build her a humid hide.

Ditch the bark and replace with paper towels.

Stop spritzing to maintain humidity.

Now about the vet - one of the things you can get from a vet for very little money is a tube of silver sulfadiazine. Silver sulfa is the silver bullet of antibiotic ointments. Having a tube of this stuff on hand is a must have for any snake keeper. Despite what people will tell you, neosporin is not only NOT equal to silver sulfa, but it has some undesirable side effects.