I had unprotected oral sex 3 weeks ago. Prior to the exposure I was extremely concerned about contracting an STD. At the 3 week post exposure I took a HSV1+2 igg and igm test, both came back negative. I have been extremely concerned with the burning sensation I get at night in my urethra, at the tip of my penis. This morning I noticed a light grey watery discharge from my penis it was very little. What are the odds of contracting an STD due to my experience. Also does the time frame in which I took the herpes test render a false negative? Also what STD is characterised by grey watery discharge?