He wobbles faintly whenever he moves/lifts his head, and has missed several strikes when going for his food.

They keep them in plastic tubs at the store; if you think this is caused by the heat I'll get in contact.
He hasn't been exposed to any chemicals while I've had him, and the wobble was noticeable when we got him, so chances are it was either the store or the breeders they bought him from.