So, recently, my Boa's been acting a little funky. His husbandry has been perfect as far as things go, and I thought he was just acting a little weird because he was in shed.

Recently, he's been hissing at me whenever I walk up to the cage to give him water or to organize and clean stuff above his cage. He hadn't hissed or shown any aggressive behavior before and I thought he was just crabby because he was going blue.

2 feedings ago, I was trying to feed him live (He's not very picky, so I switch around food items depending on what I have with him.) but he wouldn't take it and bit at it (more of a fear/aggressive bite) and got a huge mouth full of aspen. I took him out and opened his mouth to help pull some of the aspen out with tweezers. Then he ate PK in a heartbeat.

Today, I was checking up on him, and I took him out for a bit. I noticed an odd popping sound. He'd open his mouth slightly and occasionally his throat would puff out. He also would make this rare wheeze that sounded a lot like a hiss does.
I looked in his mouth and didn't see anything unusual, and there were no bubbles or discharge.

Obviously I'm taking him to the vet. However, what do you guys think? Could he just be being a little aggressive outside his cage? Puffing up his throat, slight hissing, popping sounds?

He's never attempted to bite me, but I haven't really given him the chance.