feel pain in my prostate, and had no sexual relationship

i had bacteria in my prostate most probably from sexual relationship, and the doctor told me to take antibiotics like tavanic, i did use it, then i made analysis, and found out that there are pus cells but no growth which means there is no bacteria, after a 6 months, i felt pain and i made another analysis, which showed that there are bacteria again, so i took the course once more, and i got healed, the doctor said that maybe i got bacteria again from sexual relationship, now after 6 months, i feel pain in my prostate, and i had no sexual relationship, why i always have pus cells? and did my prostate become vulnerable to any bacteria?