I am a male 28 and about 6 weeks ago I had unprotected sex with a woman. 1 week later, to ease my mind, I had a STD panel done that test for the major STDs, plus I had an early detection test for Herpes. Everything but he HSV-1 came back negative. I have had cold sore since I was 10 probably. After the test (a day or two), I started having some pain at the tip of my penis. It is a sore aching pain that is tough to describe. I had no burning during urination, no discharge, and no other physical signs of an STD. However, it had me worried so I went to a doctor and also retook all the previous STD test I mentioned. The doctor visit and tests were at 3 weeks and 4 days after the encounter. Doctor said he saw nothing wrong with a visual inspection, and a few days later the test, all but the HSV-1, came back negative. The pain I had, seemed to go away about 2 or 3 days later.
At 6 weeks the pain at the tip of my penis seems to have returned. It seems a bit more intense this time. I see no physical signs of anything expect maybe a very slight redness running in line with the opening ot my urethra. No discharge, no bumps, swelling, or burning within the penis or urethra while urinating. It seems the pain is more on the outside I think. I guess the pain could be descibe as a burning but not due to urinating. I have called the testing center and they say they are as positive as they can be that it is not an STD related issue, but what could have caused this and is it just by chance it happens after a sexual encounter. I guess my question is, could the test have missed something and if not, what else could cause this?