Sterile Prostatitis

I am 27 year old male who has been having chronic pain below my belly button and my left testicle for more than a year. I was first told that I have a urinal tract infection, which was a year ago was given a treatment of antibiotics. I have now been diagnosed as having Sterile Prostatitis and I have been given Levofloxacin tablets to take orally. My question is what does Sterile Prostatitis really mean, I have tried to look it up on the net but its not very clear to me, it seems there is still some debate as to its Causes and symptoms.