It is very unlikely you have any STD from the exposure described. First, statistically, it is unlikely a partner like you describe would have a transmissible STD that could cause such symptoms. Second, even with infected partners, most exposures don't result in STD transmission. Third, the unprotected exposure was brief. Fourth, the standard gonorrhea and chlamydia tests are highly reliable and 8 days is plenty of time for accurate results. (That is, your fear of false negative results is not really justified.) Fifth, STDs almost never cause "stinging" of the penile tip. The main symptoms are discharge from the penis or penile blisters or sores, not stinging alone.

Anxiety over a regretted sexual exposures is a common explanation for symptoms like yours. Anxiety and psychological factors commonly magnify trivial symptoms, or even normal body sensations that you otherwise would ignore or not even notice. However, you're in a much better position that I am to judge whether this might be likely in your case. But I see no reason for additional testing and if somehow I were in your situation, I would continue unprotected sex with my wife without worry I could infect her with any STD from the exposure described. If your symptoms continue or you otherwise remain concerned, you could return to your doctor for further evaluation. But I'm confident nothing serious is wrong.

I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD