left side flank pain with wbc in urine no bacterial growth

I have been having left sided flank pain since august of 2007. Pain started as dull pain that would never go away to suddenly sharp then back to nagging pain. I also have noticed white string floating in urine and I notice that I go to pee less during the day than i used to. My labs keep coming back normal. I have seen 2 general doctor 4 urologists 2 nephrologists 1 neurologist 2 GI doctors 1 ob/gyn and none have been able to give me any answers. All my labs keep coming back normal except High white blood cells in the urine but no bacterial growth. They have also found small amounts of red blood cells. I have had about 2 abdominal CT scans 2 Ultrasounds and 1 renal scan that have all come back normal. I just find it so hard to beleive that not 1 doctor has been able to help me at all. One doctor gave me ultram and it was the only thing that helped with the pain but he only gave me 15 pills and I finished those along time ago and when I asked him if I could get more he wouldn't write me another prescription. I just want to give up sometimes. I am only 33 years and I don't want to live with this pain anymore. If i was competely fine why do I keep having white stuff floating in my urine accompanied with pain. Can someone shed some lite on this for me.