What to do when you develop hives to your own sweat and the sun?

Cholinergic urticari. Cholinergic urticaria is a condition in which hives occur in response to an increased body core temperature either from exercise, fever, hot showers or sometimes sun exposure. There is also a condition called solar-urticaria caused by sun exposure only, and another condition called exercise-induced urticaria that is also different from cholinergic urticaria. See an allergist for accurate diagnosis.