Yes, if it's a RI, you need to bump the humidity to help him break up the mucus. And he needs to be seen by a vet so that you can start him on rounds of injectible antibiotics. If it's advanced to drooling, then it's not going to go away without treatment.

No one can diagnose your snake just based on a description, and none of us are vets. But if it was MY snake, I'd be making a vet appointment.