My almost 2 month old arches his back and keeps his head back when im burping him sometimes. like hes fighting it, he also has reflux so could it be a symptom of that?

This is not uncommon. The back muscles are some of the first that an infants developing nervous system gives them control. Stiffening is a non-specific "I am pissed off" move to anything they are unhappy with. This added to crying are how they respond with control. Give the kid a few months and this is less prominent as they begin to control other muscle groups.

Agree with Dr Ferguson. This could just be a normal thing that babies do...however, it also could be part of his reflux; please discuss with his pediatrician.