I have heard that lactose intolerance can cause skin conditions; perhaps that it. You could just try lactose free milk if that’s the case. Never tried rice milk and to be honest, I don’t really want to.
When I drink milk, I go organic and depending on who’s staying with me, lactose free.
I believe that was the reason the doctor said was it can be related to lactose intolerance.
He also sugested keeping him away from sugar, and highly processed foods.