Did you see fleas before you started the medication? It will be OK to use DERMA-OPNX while your cat is on the flea med. Just give it at a separate time. You might want to look at some of our products to help the skin. DERMA-IONX which is an oral homeopathic product stimulates the enzyme systems in the body which 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 probiotics are helpfully in restoring the intestinal flora after the effects of the medication. These supplements together with DERMA-IONX can produce a synergistic response. I would also suggest that you give your cat only filtered water for drinking and bathing if your water contains chlorine or fluoride.
For the dietary modifications you might want o try a grain free diet and feeding cooling foods according to Chinese food therapy. Fish and turkey are considered to be cooling. Chicken and lamb are warming. Of course if your cat has a food sensitivity to a particular food do not give that food.
It would be a good idea to bring a stool sample to your veterinarian to have it checked for the presence of parasites. Many pets acquire tapeworms from fleas. Tapeworms can create poor skin and coat. Please feel free to contact us again if you have any other questions.