Hellppp

[Bogertophis]

What are you trying to feed him? mice, rats? size/age? live or f/t? I'd be offering live for maximum interest on his part (esp. if he was fed live before) BUT nothing
bigger than young hopper (mouse) w/ eyes barely open, or rat pups (eyes closed). What was he fed before? (rats or mice? best to stick w/ whatever worked for now).
You might also try f/t since he's not up to constricting live, it sounds like? (even if he didn't take it before, he might now?)

Hydration is essential to life, more than food, for a snake in bad shape & dehydrated. A snake cannot digest without adequate hydration, so you need to encourage
him to drink, keep up the humidity in enclosure, & maybe give him a gentle soak in lukewarm water (not deep, NO swimming needed) before pushing food. Mites
cause dehydration & can cause organ failure, nothing to be trifled with. Not aware of mites leaving bite marks-? but use either Betadine (povidone-iodine) dabbed
on & let dry, or get some Vetericyn gel (water-based, made for snake use) from pet stores or Amazon (I think Petco carries it, etc). Don't know why his stomach is
yellowish- especially without seeing it. That's rather concerning...best bet might be a qualified herp vet. Good luck.