My urine is very dark color, and urologist says there is blood in urine. The problem is that the source is unknown, and quite puzzling. I have had scans to no avail. Cystoscopy shows no lesion or tumors. I have had a series of urinary infections recently, with source of infection also unknown. Currently on a reduced dose of Bactrim to keep infection away. Does this condition sound familiar in any way? Any response appreciated.