Thank you for the very clear explanation.
Trichomonas is a very unlikely explanation for this problem.
Welcome to the forum. I'll try to help.
It is rare for symptoms of urethral (lower urinary tract) STDs to start more than 10-14 days after a sexual exposure. And even in persons with relatively high risk exposures, STDs are quite uncommon in persons over 40 years old, even rarer at age 60. Further, non-STD urinary tract infections (UTI) are very frequent at that age and in the presence of an enlarged prostate. Finally, urethral STDs almost always cause discharge; painful or urgent urination, without discharge, usually indicates UTI, not an STD.
For those reasons, it is much more likely that your symptoms were due to a non-STD UTI, or directly to your prostate gland, than to anything you caught during the sexual exposure a few weeks earlier.
A standard urine culture does not pick up STD. For example, if someone with gonorrhea or chlamydia doesn't tell the doctor or clinic s/he is concerned about STDs, a standard urine culture will be negative. (My guess is you didn't tell your doctor about your sexual exposure, right?) Still, that doesn't mean you have an STD. Some UTI's are missed by standard culture, and prostate infections or inflammation usually have negative urine cultures as well.
If your symptoms clear up on ciprofloxacin, that should settle the issue; it's a good drug for those prostate problems caused by bacterial infection. However, it is not ideal for gonorrhea or chlamydia. While I still think those are unlikely, if your symptoms persist tell the urologist about the sexual exposure then follow his advice about possible additional testing and alternative antibiotics. For now, I do not think it is necessary to discuss this with your partner. It is unlikely your current problem has anything to do with the sexual exposure.
I hope this helps. Regards-- HHH, MD
He was not, in fact he has never heard of trichomoniasis before.
Was he tested for trichomoniasis?