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 digestive enzymes, probiotics, vitamin C, MSM, and fish oil. The probiotics are especially helpful for alleviating the constipation. Be sure to look at Vet-Ionx's Canine Probiotic.
Derma-IonX can also be used topically if there are troublesome spots on the skin.
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 for a while.
Please feel free to contact us again if you have any other questions.