There are some pictures of snakes with mouth rot (AKA Infectious somatitis) on this forum. Use the search function to see them.

It sure sounds like a case of mouth rot, and it is highly contagious. As cases of mouth rot progress, they often lead to respiratory infections and bleeding gums. The "lips" (labial scales) fail to close properly, and they become discolored. Then a caseous, or cheesy, substance forms along the gums. At this point, it is very difficult to treat at home. Your vet will administer antibiotics, and instruct you about how to clean the gums and administer the betadine. It's a bit tricky if you choose to use a cotton swab because the cotton can easily get stuck in the teeth, which can be difficult to remove without loosening the teeth. Therefore, one-on-one instruction from a vet is the best course of action.

Rick