urticaria triggered by masturbation

I had had urticaria (hives) for over a month now and during this period I discovered that whenever I masturbate that's when my hives are triggered. any body can explain ?

Have you heard of post-orgasmic illness syndrome? There’s a wikipedia article on it. It’s more of a general malaise but it seems as though it may be an autoimmune response, which could certainly explain hives. Unfortunately there is next to no research on this.