Welcome to our Forum.  I'll try to help.  Let me first point out that at this point there is no evidence that you have and STI that needs or would benefit from treatment.  Most commercial sex workers do not have STIs and oral sex only relatively rarely leads to infection.  When it does, the most common problems are either gonorrhea of non-gonococcal urethritis NGU) caused by mouth organisms introduced in to the urethra during sex, both or which you have been repeatedly tested for and found to not have.  When it occurs, his sort of oral sex-related non-chlamydial NGU is not clearly an STI in the traditional sense, is not readily transmitted to sex partners like other STIs, and in not associated with complications.  In the United Kingdom, many specialists do not treat NGU associated with oral sex.  When treated, oral sex-related NGU typically resolves quickly.  In your case, you were treated and the problems seem to have recurred providing further evidence that this is not NGU. 

When it occurs acutely, viral infections, particularly those caused by a virus called adenovirus can cause conjunctivitis and urethral discomfort but this problem is not treatable, needing to run its course, which it typically does in a week or so without consequence, and does not cause complications.  Adenovirus urethritis does not recur in the fashion you describe. 

A swollen urethral meatus in this setting, with negative tests is most often associated with the inadvertent trauma of repeated self-examination.  Similarly, increased pre-ejaculatory fluid is not a sign of any STI. I am confident that this is not a typical STI and see no reason for further treatment of STI testing.  My advice is to not worry and let this run its course.  I think you may be noticing things you would not have noticed had you not visited the CSW and started looking for symptoms.  OTOH, if you feel you must investigate, I would see another urologist to look for some sort of coincidental problem that you began to notice about the time you visited the CSW.  I would not worry about STI and would not worry about impacting your wife's health as a result of your extramarital encounter. 

I hope that this perspective is helpful to you.EWH