You might want to look at some of our products to help heal the skin. Derma-IonX which is an oral homeopathic product stimulates the enzyme systems in the body which reduces itching and inflammation, promotes healing of 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. Together with Derma-IonX it produces a synergistic effect for a faster response. Derma-IonX can also be sprayed on the skin. 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 to try a grain free diet for a while.
Defendex shampoo which is nontoxic washes away debris and soothes the skin. However, bathing a cat is not easy so I would try the other things first. Using these products is a simple and effective way of helping resolve a difficult condition. I would also have a stool sample checked by the centrifugation method. Tape worms can contribute to skin problems.
Please feel free to contact us again if you have any other questions.