I understand the frustration of possible allergies bc I've been through it down here in pollen-ville with 2 of my kiddos. You are smart to focus in on her paw chewing bc it is indeed a cardinal sign of allergies. So, that's great of you to notice it and to keep an eye on it. Btw, how old is she?
I feed raw and I really love it. Mostly I use the Primal brand (duck). I've been using it about 5 years. If your kiddo is a picky eater, it may be worth trying raw bc there have been some other picky eaters here who then go crazy for raw. So for that reason alone, it may be worth trying it.
As for the allergies, food allergies are rare - but they do happen; only about 10-15% of the time. That said, I do think it helps enviro-allergy dogs to be on low allergen type foods. How does her skin look....especially on her belly, armpits, groin, back etc -- any red patchy areas, any inflammation at all? If yes, then def get a skin scraping asap to see if she has a skin infection.
I'm going to paste a thread here, it's a thread about how to approach allergies if you're suspicious they may be present (and I think you're correct in that they are present):
http://www.yorkietalk.com/forums/die...tart-here.html