I've been researching about RI in BP lately, because I think mine is acting strange. He yawns A LOT when I hold him, he won't eat, I've caught him stargazing, I hear popping noises when he sticks his tongue out, and he has sneezed twice since I got him on Xmas. I'm really worried for him, as this is my first pet snake. I want to know if there is an easy fix I can do, or if I have to go to the vet.

Notes:
I have a lamp and a heat pad at 90 degrees
He's on EcoEarth
He gets fresh, dechlorinated water
I try my best to keep his humidity around 60%, and it is there most of the time (I even have tin foil on the lid)
He has two hides- one on the cool side, and one on the heat pad
I gave him some climbing decor
He is in a 20 gallon atm, but he will be moved to a 40 gallon once he settles in