A single 1 gram dose of azithromycin usually is sufficient for NGU, but additional treatment is required in 10-20% of cases. Give it another week. If the symptoms continue to clear up and are gone entirely by that time, all is well. If not -- and particularly if the discharge returns -- then a second round of treatment would be recommended. That would normally be doxycycline 100 mg twice daily for 7 days, plus a single 2 gram dose of metronidazole (Flagyl) or tinidazole (Tindamax).
As for "still can’t seem rule out HSV-2 given the risk I took", you misunderstand the risks. Herpes remains unlikely. You had only a single exposure to an infected person. In monogamous couples in which one person has HSV-2, who have unprotected sex an average of 2-3 times a week, transmission occurs in only 1 in 20 couples each year -- i.e. after 10 years only half the partners become infected. That gives a clue about the low risk associated with any single exposure. To prove for sure you weren't infected, have a final HSV-2 blood test 3-4 months after the exposure. You can expect it to remain negative.
Welcome to the STD forum.
I very much doubt herpes is causing any of your symptoms. The only one that might be compatible is the irritation of the glans, but herpes rarely if ever causes the diffuse irritation/inflammation you seem to describe. If it were herpes, there would be discrete blisters or open sores, especially in an uncircumcised man. In addition, the penile skin symptoms would have started within a few days of exposure, not 2-3 weeks later. Finally, although your HSV-2 blood test was early for definitive results, 60-70% would have positive results by 4 weeks, so the negative result is moderately reassuring.
As for other causes, a yeast infection or nonspecific balanitis seems more likely. (Balanitis is the medical term for inflammation of the head of the penis; and as "nonspecific" suggests, some cases have no known obvious cause.)
Putting herpes aside, it sounds like you have nongonococcal urethritis (NGU), an entirely different STD. Chlamydia is a common cause of NGU, but explains only about 25-40% of cases. I'm somewhat surprised the NP didn't prescribe azithromycin or doxycycline -- but perhaps the urethral discharge was not so obvious at the time she examined you. In any case, you should return now and discuss treatment.
One somewhat far-out consideration might be reactive arthritis. You don't describe joint pain or inflammation, but RA is often accompanied or preceded by NGU and by certain kinds of inflammation of the penile skin, especially the glans (called circinate balanitis). Further, RA can be triggered by intestinal and rectal infections, so there could be a connection with the diarrhea that you had earlier. Your dermatologist would be an excellent source of care to consider these possibilities.
Returning to herpes, see what the NP and/or dermatologist have to say. If you remain concerned about it, you could have another HSV-2 blood test about 3 months after the sexual exposure. But I'm really not concerned you have HSV-2.
I hope this helps. Best wishes-- HHH, MD
Thank you for the invaluable recommendation and insight. I went ahead and persuaded the Physician Assistant to prescribe 1g of azithromycin. After 7 days, the discharge was subdued completely and I’m feeling little better by the day. Today the 12th day I’m still feeling sensitivity on the meatus, which is still red/irritated. But it is more pinch pain at this point. Also my glans is very dry and sticky (like post it notes). Since the initial symptoms I haven’t been able to produce smegma which is a concern. I’m applying zinc oxide which seems to help.
My concern is that the medicine may not be enough. Does it usually take this long for azithromycin to be effective? Should I wait a couple more days before requesting additional antibiotics?
Thanks again for your help Dr. Handsfield! I will still go with the HSV-2 blood test at 3+ months and report back with the results. Even though that my symptoms aren’t herpetic, I still can’t seem rule out HSV-2 given the risk I took.