Since he's going to see Mickey, I've got to share a tip one flight attendant used with a child (seemed to work). Tell him he's getting Mickey ears. Take two styrofoam (or plastic) cups. Take two paper towels, dip in very warm water, squeeze out, place folded up inside the cups, then put the cups over his ears (KWIM?). The humid warmth inside the cups will help his ear pressure. It looks a little strange, but since he's going to see the Mouse, it should be pretty fashionable.