I would eliminate the Caesar food, it's full of by-products and grains
Strip the diet down to a novel protein (rabbit, venison, duck, etc.) and no grains and see if that helps. It's an easy way to either discover or eliminate a food allergy. You could also try using the "free" type laundry detergents and fabric softeners, no dyes or perfumes.
Good luck, I hope the itching gets better
