One of the first things I did was put my ear against his body to see if I could hear any cracking/popping and I didn't. Earlier on during that day my bf had shown the snake to his friend and at that point apparently it wasn't making any noise. It appears to just be whistling, not popping. Having thought about it for a while I'm starting to doubt whether he's sick, especially since he's going into shed. Also he's supposed to be a picky eater and he's eating like a beast for us, if he were uncomfortable I figure the first thing he'd do is stop eating.

I figure the factors that differ my collection from theirs are: 1) their snakes came in the mail, mine came from expos. 2) Mine eat rodents I breed myself, theirs eat rodents from a pet shop which frequently have lung problems. 3) They misted their enclosures quite regularly, I never mist except during sheds.

We're gonna try to rule out all those factors from now on so this never happens again. Also I'm gonna take him to the vet regardless, it's not worth risking it.