Suspected food allergies

Hello I am in the middle of moving across the country and  I need some suggestions on foods to try until I can get set up with a good vet in my new area. I have a kind of tricky issue...I believe both of my cats (sisters) have food allergies. They are 5 years old. One used to have severe diarrhea 3-4 times a week that has been under control for about 2 years now. The other one has kinda gone under my nose for a little while. She's always licked the fur off her stomach and vomited about once a week. The vet thought the stomach fur issue was an anxiety issue at first and we didn't think much else but it's gotten really bad in the past few months. I took her to the vet in Feb. because I noticed she was really licking/biting her stomach, with fur missing from her belly button area to her buttocks and down into her inner thighs. She also increased vomiting to every other day, 90% of which was the dried food within 5 min of eating. At first I thought she was just a fast eater but I think since her stomach issue is getting worse that it's probably more than that. She is an indoor cat and has no fleas/dander. Her history is also remarkable for electrocution and "severe pica" to quote the vet which has been in remission for over a year now, after a 1 year course on Prozac.  Could it be possible that instead of eating other things such as clothes and plastic bags, she's now focusing that energy on herself??? The first cat in addition to a history of diarrhea also has been diagnosed with asthma. She also had a lump at the injection site of her first rabies injection years ago so I think they both have extremely overreactive immune systems. 

Before the vet visit, we were on Taste of the wild rocky mtn formula dried (been on this about 2 years) + wellness chicken canned (been on this since a baby and they don't like other flavors). The vet sent us home with Science Diet Z/d to use as the dried and cont. with Wellness canned but that produced vomiting after EVERY dried meal and the vet didn't seem to have any other options in mind. So I then tried just a Wellness only canned but this only lasted a week as they both got bored and stopped eating it. So went back on Taste of the wild dried + Wellness canned with mixed results. I think shes biting her stomach a lot more often but vomiting is back to about once a week. Prior to the Taste of the Wild dried we were on California Natural Chicken/Brown Rice dried for about another 2 years which I believe didn't mix well with the first kitty's stomach as her diarrhea symptoms cleared up a short time after leaving that food. The 2nd cat still licked her stomach on the California Naturals (we thought at the time it was a pica/anxiety issue) but it was nothing like it is now. 

I have compared ingredients in all foods, seems chicken is the common thread, and perhaps the first kitty doesn't do well with rice/brown rice? Are there any foods that don't have either of these that I can try to see how they respond? They have to eat the same foods due to my home situation/work. Any other ideas in general?? THANKS!!!!!!

ETA: She did stop licking the fur off her stomach after she had been on the Prozac for about 9 mo. We stopped giving it to her as the pica had apparently stopped and her personality had totally changed...she wanted nothing to do with me and kept to herself while she was on it but went back to her sweet self within 2 days of stopping. 

The quick answer is to try Natural Balance limited ingredient duck and green pea formula for cats with allergies. It does sound like your cats have a lot going on and finding a reputable vet in your new location is really best.

Two brands of foods that are exclusively meat + the added vitamins and minerals are: Before Grain & Evo. You could always try these to see if its a grain/carb allergy. We also have a cat with allergies and hyperesthesia and she licked the same area and removed all the hair, and she's not a pica cat, so its a common symptom when somethings upsetting the cat internally. Right now I have her on a omega-3 supplement for her skin. If these brands don't help then maybe she has a protein allergy, which is a possibility too. Evo has a venison variety in case its a poultry allergy, so thats an option as well.. if she'll eat it.

Also, if you can feed exclusively wet right now I would. It will be a lot easier to determine the allergy since wet foods have much fewer ingredients than dry (plus all the other added benefits to wet - higher protein, more moisture, etc.)

IMHO opinion I would resort to medication last if possible and there may be an holistic vet in your area who you can contact first, because in my personal opinion when it came to solving my cats allergy problem a regular vet suggested poor food brands and steroids, which did not solve the problem and caused other issues for us.

One more suggestion, when you do start changing foods, keep of journal of what worked and what didn't, it will really help later on!

Best of luck and if you have any other allergy questions feel free to send me a message.

*Sending positive kitty cat vibes your way*