It may be cost effective in the long run if you just make an appointment with a board certified veterinary dermatologist. Get intradermal skin testing, or whatever the specialist recommends, an accurate diagnosis and hopefully, effective treatment.
I doubt that the minute amounts of chemicals present in all processed foods are causing your dog’s problems.
The only potato free, grain free dog foods I am aware of are Nutrisca and Zignature.
If you are receptive to science based veterinary medicine go here. http://skeptvet.com/Blog/
