[Ellie May]

That does sound a bit like an allergy.
It could be food or environmental but my first thought is food because of the itchy ears and jaws. The only way to figure it out is to do an elimination diet and wait at least 60 or possibly 90 days when switching ingredients because it takes that long for symptoms to go away in some dogs.

If the Cal. Nat. wasn't bothering him, you may want to do that for 60 days. If his symptoms stop, then add human foods in one by one and find the trigger....