if it's not a uti what is it? This is kinda long.

I went in to the emergency room and explained everything I had going on and they did pee sample and said I had no infection no nothing. It's been going on for about 8 months. Some days it burns some days it doesn't. It pisses me off because it only seems to do it when I get ready to go have a good time. Anybody know what it could be since it's no infection?