Most dogs with food allergies also have environmental allergies. Environmental allergies don't have to occur only from things that are outside. Dust mites, storage mites and
indoorIndoor/outdoor allergy relief molds are high
allergensAllergen
Positive reaction to allergen also. Since
allergensAllergen
Positive reaction to allergen penetrate dogs skin it is good to bathe your dog very frequently (once per week) with medicated, hypoallergenic shampoo. Environment allergies are impossible to
controlControl
Control rx. A Hepa air filter will help for
indoorIndoor/outdoor allergy relief and outdoor allergens. It may also help to get your dog tested for enviromental allergies so that you can desensitize him to them, or try to eliminate them from the environment. You may also need medications at certain times of the year to help control the allergies. A good choice of medication is Temeril P which is an anti-histamine and steroid combination. There are some herbal formulas that would help also such as: Nettles tincture or the Chinese herbal formula called San Ren Tang, both are available online.
A fish ad potato food trial takes at least 3 months. Have you noticed any improvement in this time? Good Luck!