I would say it's definitely diet related. They need to find out what food allergies he might have. In my experience with all kinds of ailments with family and friends, every single one of them was "cured" by diet alone - including my son's Crohn's disease. I agree with whoever said no lotion will help - it won't. It is something internal. Also, it might seem trivial, but make sure he is staying hydrated, drinking plenty of water - that will also affect the dryness of skin.