One month is not very long to be working on allergies so do not give up hope. The supplements I use along with Derma-IonX include digestive enzymes, probiotics, Vitamin C, MSM, and fish oil. Together with Derma-IonX it produces a synergistic effect for a faster response. I would also suggest that you give your dog only filtered water for drinking and bathing if your water contains chlorine or fluoride.
I am glad you have switched to a grain free food. If your dog is not allergic to these protein sources, fish or turkey (are cooling foods)is preferable to lamb or chicken (are warming foods). You might also get some homeopathic Thuja 30C from the health food store and give one pellet at bedtime for 3 weeks. Sometimes this can help to re-balance the immune system.
Defendex shampoo which was designed to fight against fleas and mites also washes away debris and soothes the skin and reduce itching. In between baths, I would rinse off or wipe off the feet after walking outside.
Please let us know of your progress.