Is he yawning and holding his head up trying to get air into his lungs? I would suggest going to the vet but we have never had any luck with meds prescribed by them and it was way too expensive to get a culture done for the 13 snakes we had sick (yeah haf an outbreak at the beginning of owning snakes). Cultures are need so the vet knows what meds to prescribe. We have had the best luck with a medicine from TSC called liquamycin. I in no way suggest you use it, i am only stating what we do. Go to a vet.