DERMA-IONX is helpful for a variety of skin conditions. It is an oral homeopathic product which stimulates the enzyme systems in the body that aid the skin and helps with assimilation of nutritional components in diet and supplements. The supplements I use along with it include Probiotics and Omega 3,6,9. The OMEGA 3.6.9 is especially helpful for soothing the skin. These supplements together with DERMA-IONX can produce a synergistic response. I would also suggest that you give your dog only filtered water for drinking and bathing if your water contains chlorine or fluoride. DERMA-IONX can also be sprayed onto the skin to provide topical relief.
For the dietary modifications you might want to try a grain free diet and feed cooling foods according to Chinese food therapy. If your dog is warm and seeks cool places to relax in he might do better with the cooling diet. Fish and turkey are considered to be cooling so would be better choices than chicken or lamb which are warming. Of course if your dog has a food sensitivity to a particular food do not give that food. (Beef is neutral.)
If you need to bathe, DEFENDEX shampoo is soothing. I like to use it because it is nontoxic.
Do you know what your dog is allergic to? Please keep us informed so we can help guide you along the way.