I found it! So I’m still “breaking out” in a rash when I work out, if I work out hard. I was goofing around on a dermatologist site looking for other things and came across a name for my “work out allergy,” Cholinergic urticaria.
Cholinergic urticaria is often thought of as a young person’s hiving and tends to affect those in their early teens through mid 30’s and is seen more commonly in males. This physical urticaria is due to the presence of adrenaline that causes the mast cells to degranulate. Cholinergic urticaria has a very specific appearance, forming multiple tiny pink or red bumps, often only in certain areas of higher blood flow/sweat formation to the skin. Cholinergic urticaria tends to have an abrupt onset and lasts for only between 30-60 minutes. Anything that causes an increase in adrenaline (exercise, stress, heat exposure) can trigger this condition.
Derma Doctor