I tried hydrocortisone the first time it happened. Nothing. Then I tried Benadryl. It worked better. So the second time, I went with Benadryl from the beginning, and it made them fade a lot faster, and I didn't get the dark spots the next day.

I am definitely not allergic to latex. I've worn plenty of latex bandages in extreme weather conditions with no problems. My niece has a latex allergy (skin allergy only, not respiratory..she can be in the same room with balloons etc.) and I've never had any of the problems she has coming in contact with latex in clothing or bandages. Plus, my shorts have silicone grippers and not elastic. Nor are the hives under my shorts, only on the tanned parts of my legs.

My hands get contact dermatitis when I handle certain soils. Maybe it's prolonged exposure to crap on the road plus sun exposure? I dunno. It definitely seems to be an allergic reaction of some sort.