Have you tried Benedryl? I know that sounds too good to be true, but my dogs get the redness, puffiness, sores on their pads a couple of times a year, and it's attributed to seasonal allergies.
My vet recommended I try Benedryl, and I've not looked back. I start in September, and they take it through November, then again in March through May (those are my girl's allergy seasons).
Check with your vet on the dose, but it's gotta be worth a shot, right?