Is It Safe To Take Doxy For Ureaplasma Urealyticum?

I am experience severe genital problem. When we had intercourse in Sept 2014, I started having severe symptoms like painful urination, painful ejaculation, severe pain in perineum, painful bowl movement, foul smelling urine, chills ..etc. I got treated with Rocephin 250mg / 1g Zithromax. Symptoms went down for a week then started again, went back again in 4 weeks and got treatment Rocephin 250mg / 2g Zithromax. Nothing came positive for standard STDs. Again in 2 weeks symptoms came back and tested positive for Ureaplasma Urealyticum. I started taking Doxy 100mg twice a day for last 6 weeks but the symptoms are coming on and off like few days feel better but symptoms are not gone completely. I am not sure, when my prostate got infected or its bacteria resistant for doxy. I am in big confusion and going around Urologists and nothing concrete diagnosis. PSA is normal, DRE test is normal. PLease advise and really great help for me.