advice for dealing with food allergy rash?

After four months, several vet visits, and a couple different food trials, it's pretty well been determined that my older cat has some severe food allergies. While the vet has said there's not much that can be done for her rash until we figure out what's causing it beyond the shots she's been given to suppress the allergic reaction, I was wondering if anyone had any advice on managing the rash in other ways. Our most recent attempt at a single protein diet, lamb, exacerbated her skin issue something fierce after only a week and a half, and she now has a rather awful row of raw sores down her back. I've been washing them and putting antibiotic salve on the places where they've cracked open to help them heal, but I would appreciate any other advice that could be provided.

Maybe the problem is not the protein but one of the additives in the commercially prepared food.  If I had this problem, I would definitely explore the various raw and homemade diets recommended in the Nutrition Forum before trying any more commercially prepared food.  I remember reading one thread where it turned out the cat was allergic to one of the super common additives, perhaps guar gum, which is found in just about everything commercial.  Home made food was the only way for this owner to avoid it, and that worked.

@penofdl, I have been in a discussion in another thread with someone whose cat has similar raw sores on her back. They have gone through a series of various trials and are currently on another. Perhaps something there might spark an idea or something to try. Here's the thread:

http://www.thecatsite.com/t/276821/infected-nailbeds-and-infected-areas-on-back

Wow great job managing through all the diet trials!

Rashes, staph bacteria on the skin, yeast, and parasites all need to disappear first in order for me to figure out if a patient is truly food sensitive. It's my first goal. Because then they are more comfortable. Plus, the inflammation begets more inflammation. The infection begets more infection. And it can mask the true results of your allergy trial! Frustrating, right? 

Im always going to tape n' scrape. That is, do cytology on your cat (put sticky tape on them, scrape the skin, look under the microscope). With those results in hand, you'll know what meds to use to make the rashes disappear (they really need to be history first or you will want to pull your hair out figuring out what the true allergy is). The meds are given at the same time as the food.

So, If you have been through months of food trials - then you are actually really, really close to getting the true diagnosis. But you need some tape n' scrape action (if it hasn't been done yet). Then get rid of the underlying organisms causing the rash! Or they need something to control the out of control skin immune system (allergy medication) until the food can kick in (assuming it's really food allergy).

Good luck!

Dr. Kris