Nitro has terrible environmental allergies. We thought they were food related, but after switching to a raw diet, the allergies are still there.
Nitro gets 4 benadryl a day, and i have STILL had to put him on prednisone this last time, AGAIN!!!!! He's a food monster on pred, but i have reduced his dose to half, so that he doesn't get the hunger pangs, but it's still working inthe background, he's a lot less itchy than he was, thankfully.
I use Fish oils 1200mg a day each dog, plus a moisture mist conditioner by veterinarians best ( petsmart around $15) I use a medicated shampoo that i got from my vet, or i use an oatmeal and aloe one by Earthbath.
Saying that however, Nitro is also Hypothyroid, which affects their coats and leaves them vulnerable to ear and skin infections, plus dries their skin out, if not properly medicated.
If you feel that his itchying is getting out of control, you can go to your vets and get a vetalog shot, it's about $20 at my vets, that will cut the itch cycle. It works for about 2-3 weeks, which will give him the chance to let his skin heal.
Also if he's biting or scratching his skin raw, go to petsmart and get some DermCare, it's a blue topical liquid, you can either dilute it and use it as a wash or you can apply it direct from the bottle twice a day, it's a wound wash, with an antiseptic in it. It will stop any infection setting in. My vet manager told me about DermCare and i wouldn't ever be caught without it. It's been a god send.
Also another topical solution you can try is a 1/2 and 1/2 solution of Apple Cider Vinegar and Water, in a spray bottle. Spray your dog down with it, it stops the itch. Strange but true. Or you can put a tablespoon in with his food or have him take it off the spoon.