Unfortunately, NSU is just a term given when they don't discover which specific infection you had. Recurrent NSU is unfortunately both common and problematic. My recommendation is that you be tested for Trichomonas, Ureaplasma, Mycoplasma, and Chlamydia. Those are the most common causes of NSU. Chlamyida is the most common, but also the least likely to reoccur. Some of these tests are at this point uncommon, but you can get them ordered through LabCorp.
Trich test:
http://www.labcorp.com/datasets/labcorp/html/chapter/mono/sm000300.htm
Mycoplasma/Ureaplasma, Real-Time PCR
http://www.labcorp.com/datasets/labcorp/html/chapter/mono/vm003300.htm
The problem is many doctors will simply treat with antibiotics, but without knowing which organism you're treating, that can often fail.
If you'd rather just be treated with another round of antibiotics, then I'd suggest 2g Azithromycin and 2g Flagyl. The Azithromycin will treat the bacterial causes of NSU and the Flagyl will treat Trichomonas. If you revisit the doctor who first treated you, chances are good that they will recommend this treatment as it would be standard for a second round of NSU. This would be a cheaper alternative than testing. Good luck.
I had the STD Called Non Specific Uthretus, aka NSU..What do u think i will have now
It's possible that the antibiotics didn't fully cure your disease. Which STD did you have? Some are easier to get rid of (chlamydia) than others (like ureaplasma). Sometimes antibiotics will just reduce the infection without curing it. Did you test negative for what you tested positive for after treatment?
Also, yes antibiotics can cause symptoms, like a fixed drug reaction, but I don't believe what you have would be a typical case of that.
If you are sure you're cured, then you might have prostatitis, or chronic male pelvic pain. That is not unusual after a bout of a STD. You can read up on those on Google.