Food allergy or something else?

New member here. I have A tabby she is about 8 years old and this all started almost three years ago. I moved in to a new house with a friend who had a big dog. I started giving my girl this fish food and about a month later she started licking and pulling her hair out. It started on her belly and then was all over her back near her bum as well. Went to the vet and she was given a steroid and it went away and came back with vengence a month later. Now i have seen 3 different vets and spent well over a thousand dollars, she has had blood work done, been on evey type of limited ingredient food, steroids, and finally was on Atopica which is just cyclosporine, but cyclosporine is backordered so that only lasted a month. The steroids helped but once it was out of her system she would go right back to licking and pulling her hair out. Atopica worked but same thing once it was out of her system she went back to licking and pulling her hair out. I haven't had the allergy blood test done yet. She also rubs her bum across the floor so i am wondering if she might have a really bad ringworm. Has anyone had this problem and how did they solve it? I have just about had with Vets, i feel like all they care about is making as much money from you and not fixing the problem. Please help if you have had anything like this, i am just about out of options and like i said i am fed up with vets and don't know if i can trust them anymore.

I'm sorry you're going through this.  One thing I would do is get a Feliway plug in or two and run them in your home to decrease any stress as it might've been triggered by stess of the move and the dog.  You can always ask the vet to do a scrape and culture of any of the lesions to determine if there's ringworm.  What foods have you tried?  Do you still feed her fish?  Have you tried grain free?

I tried the Feliway and I didn't see any results that justified the cost of it. The first vet i saw didn't do a scrape but they did pull some hair from the lesion area but it came back negative. The food trial that I have done is all with dry food and it has shone me that foods with fish, chicken, turkey, and possibly duck she gets more aggressive with her licking. Grain free foods with any of those ingredients listed I get the same results. Right now I am trying deer that is very limited in it's ingredients. The brand of the current food is Holistic Feline caviar and is single protein, single carb, no gluten, no potato. This food has been fed to my girl for about two weeks now and she is still licking a lot like usual but some lesions that had come in a few weeks ago they have since dried up. The brands of food I have tried are, SD, Natures variety LI, blue buffalo and some special vet cat food that was pushed by the vet. I have tried the pre-made raw food from I think it was natures variety but my girl turned her nose up and never touched it. Before all of this started about 3 years ago she was eating just meow mix and grew up around dogs and never pulled her hair out like this. 

I was going to suggest a condition called Psychogenic Alopecia, which is something my cat DeeJay has, she pulls out all the hair on her belly, rear legs and back feet.  We too tried every treatment, diets, steroids etc, but finally came to the conclusion she has a behavioral issue.  I don't medicate her because she is EXTREMELY difficult to get medication into.  Have you tried any behavioral drugs with her?  How long are you keeping her on each of the diets?  It can take a minimum of 6 weeks for the diet to fully get into their system, a food trial should last 12 weeks ideally.  Here is a good article that talks about hair chewing in cats: http://www.2ndchance.info/pawlickCat.htm