I was having allergy shots given to my dog every 6-8 weeks. Without them he would chew constantly at his legs and the small of his back. A lady at a local pet shop suggested he may have food allergies. I've had him on Zignature Lamb for about 4 months now. He does not require the injections any longer.
It's a limited ingredient food, no wheat products or artificial colors. He has done exceptionally well with it. It may be worth a try. A 13 lb bag is around $35 but for him that's roughly a 4 month supply. A 4 lb bag is $15. I also make his treats now using a recipe I found that I substitute wheat flour with rice flour.
BTW, the vet never suggested a food allergy or change. They were fine to give him shots without finding a solution. He will be seeing a new vet next month.
Zignature Your Pet's Signature Dish for Life!