DERMA-IONX is helpful for skin conditions associated with allergies. It is an oral homeopathic product which stimulates the enzyme systems in the body that aids 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 give a half dose on the breakfast and supper food. After there are signs of improvement you can give a whole dose once a day. I would also suggest that you give your dog only filtered water for drinking and bathing if your water contains chlorine or fluoride.
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.
Please keep us updated so we can help guide you along the way. If you want, you can start with DERMA-IONX and add the other supplements later. But I think you will get faster results if you put it all together.