Welcome to our Forum. I'll try to help. The exposure you describe was condom protected and therefor safe sex. Further, your symptoms began a day or two after your exposure- sooner than occurs for any STI. You now have negative tests and have been treated on more than one occasion for possible STIs even though your tests are negative. It is time to move on.
Let's work through your questions:
• Can I trust the post prostatic massage urethral swab PCR test sent to UK bearing in mind I had received medication 10 days earlier ? I was still symptomatic when the urethral swab was taken.
Yes, the result indicates that either you did not have an infection or, if you did, that the infection you had has been successfully cured. If your symptoms had been due to an STI, the tests would have been positive.
• Can I consider myself safe to my wife for these 7 STDs (other than herpes I know) based on the negative results ? I have informed her of the incident but not the symptoms of pain.
Yes, it is safe to have unprotected sex with your wife.
• What are the other potential causes of the elevated WBC and RBC in the urine if not due to some sort of STD infection ?
A small amount of WBC or RBC can be normally present in the urine. Other problems such as kidney stones can cause some of these problems as well. You have no evidence fo having an STI of any sort despite your continuing symptoms.
• I am aware that in a good proportion of cases no cause is found for NSU. What does this mean for prognosis and also risk of passing on some unknown pathogen ?
In persons with persistent, pathogen negative urethritis, there is no evidence that there is risk of infection for sexual partners.
Medication wise; where do I go from here ?
I owuld not treat further. It is time for you to move forward and not worry further
I hope these comments are helpful. EWH