Hello, I have a condition/disease known as Interstitial Cystitis. Basically it makes you feel like you ALWAYS have a Bladder or Urinary tract infection. Does the Doctor continue to culture your urine? If not, ask them to retest you to see if you still have bacteria in your urine? Or I am pretty sure you can buy test strips at your local pharmacy now. Also, If you have cloudy urine and/or it smells like sulfur then possibly you just have a stubborn infection.
My experience took 4 years and a LOT of research and persistance on my part. Just remember Doctors are normal people just like you or I. They possess the same ability to read and learn as you or I do. DO NOT place them above yourself or your own feelings in regards to YOUR body. No ONE know more better what's going on in your body than you. Don't take their answers as the be all end all. If you don't think it's right then persue the subject until YOU are satisfied with whatever the outcome is.