Two weeks ago I ate a fish taco (do so all the time) and within minutes I developed hot, stinging, prickly heat on the top part of both my hands. Between my fingers were inflamed bumps and within an hour red bumps covered both forearms. It stopped itching in about two hours, however, ever since then, if I expose my hands to heat (sun, cooking, BBQ), it reoccurs and the knuckles turn red on each hand and sting/itch. It's only the big and pointer finger knuckle on each hand. Very symmetrical.