About two weeks ago, I started to have protected sex with a girl I used to know pretty well. I don't think she is too sexually promiscuous, but I am not completely sure. We also had some pretty intense dry sex where my penis may have come into contact with her vagina, but I am not completely certain.
A few days later, I began to experience pain in my urethra and penis, but to this date I have had no discharge or inflammation. I continue to experience pain in my urethra and penis with some tenderness in my testicles, especially after ejaculation. I also experience no pain during urination, but feel some irritation and tingling afterward. Could this possibly be an STD?
I have been tested for chlamydia, gonorrhea, and syphilis, which turned out negative. I have also been experiencing loose stools for the last two weeks, and I'm wondering if my urethra has been infected by some other type of bacteria. I have seen a few physicians, who tell me that I am probably just being paranoid. Am I overreacting, and how can I make this pain go away?