Clear pictures of what you're seeing would help us offer constructive advice.

The only thing I can suggest at the moment, is to start looking for a knowledgeable reptile-experienced vet you can take him to. Not saying you need to rush off to a vet right away, but start looking now, so if you do decide you need to go, you'll have one lined up already. In the meantime, keep a close eye on it and see if it changes at all or gets worse in any way. It may be something simple that resolves itself, such as a tooth lost in the feeding process...or it may be some kind of infection in the mouth that will require a vet's attention. Watch it over the weekend, keep the enclosure clean and warm, and try not to bother the snake too much. Stress will weaken the immune system, and you don't want that if an infection is trying to rear its ugly head.