My son has what looks like athletes foot, but on his hands. HIs palms are cracked, peeling and dry;partially becausse of constantly itching the palms. His skin connecting his fingers is inflamed and peeling. Hands started with bumps and itchyness, and his feet had the same bumps, but not as itchy. He says his hands are itchy and dry, but his feet only showed the bumps; not the dryness or itchyness. What are the most likely causes of this condition