Does ngu cause prostatitis. received oral sex 6 months ago. told i had ngu 3 weeks after. all std tests neg. all urethral swabs since have been clear?

Separate problems: Nongonococcal urethritis (NGU) and prostatitis are separate problems, although they have overlapping symptoms and often difficult to distinguish from one another. NGU is not known to be a cause of prostatitis, but this is uncertain and controversial. If you haven't been seen in one of UK's excellent NHS GUM clinics, that would be a good next step for truly expert care. Good luck!