Hello and welcome to YT...so sorry it's under these circumstances
. Your poor baby.
It seems like 2 separate things happened to coincide here...the allergy issues along w/ something neck/spine/neuro related. If it were me, I'd probably keep treating w/ the Apoquel since it provided such much needed relief for her. Then, I'd probably be seeking out a neurologist for the other issue going on. So the xrays of the neck area show nothing...?