My dad always seems to get a rash when we are out in the sun/water, and we're trying to figure out what it is. We're vacationing in Cozumel, and he can hardly go outside because it's driving him so mad.

The symptoms include large red areas of slightly raised skin, which are warm to the touch, and itch terribly. It has spread from his sides, on his forearms, and legs. It's not sun rash, heat rash, PMLE, or any of those that I've seen so far..It's not blisters at all, it appears just like normal skin, except raised, red, and hot.

Any ideas? Or ideas how to prevent the itch so he can enjoy the water? We'll be seeing a dermatologist when we go back home.