I have had similar thing happen to me. except it started when i was younger and before i got sexual active. Sometimes it happens in my armpits (rarely). To be honest I don't belive its a std but toxin build up or something in the sweat. I have hardly no fruit in my diet and think this maybe the cause, I wish someone would back up my ideal or tell me what to do to fix the problem. Although sometimes if i keep up a good exercise schdule then it goes away. . So does anyone know whats going on? is it a toxin in the sweat, some wierd disorder. or a std.