Hi, I Have Constant Right Flank Pain For About One

hi, I have constant right flank pain for about one year. i have gone through many diagnostic tests and procedures and all were negative except for persistent microscopic hematuria and low grade fever. could it be interstitial cystitis? i have read that it is difficult to diagnose. note that I had uretroscope and the doctor told me that all my urinary tract were perfect including the bladder. could it be possible that they miss the cystitis?