So About A Week And A Half After Sleeping With

So about a week and a half after sleeping with a sexual partner I noticed an irritation in the genital region. Nothing too painful. Just irritating. Like a blister. It went away in about a week and came back a month later and again was gone in a week. It has not shown up again for just over two months now. Naturally I thought it might be herpes. I asked my two most recent sexual partners if they were clean and they both assured me they were. If it is not herpes what else could it possibly have been? I did notice that I was masturbating much more frequently than normal just prior to the irritation showing up in both cases. Could that have caused it?