It is likely you have nongonococcal urethritis (NGU) that you acquired during the sexual exposure you describe. Your urine tests undoubtedly were for gonorrhea and chlamydia, and you can be confident you don't have either of those infections. However, only about 1/3 of NGU cases are caused by chlamydia, so you are in the majority of NGU cases not due to chlamydia. But the treatment is the same, typcally azithromycin (my first choice) or doxycycline. Return to your provider, preferably at a time when you haven't urinated for at least 3-4 hr (better chance s/he will be able to observe the discharge); or if not confident your provider is up to speed on STDs, visit your local health department STD clinic.
Good luck-- HHH, MD