Hives getting better with exercise.

I've been diagnosed with chronic idiopathic urticaria. I've been on hyrdoxyzine, which worked for a while and then stopped, and ranitadine.

I like to run, and seem to have noticed a correlation between running and the severity of my hives. Namely, the days after I run they seem better. Has anyone else seen something like this? Everything I can see online suggests that exercise would make them worse.