Hello there, thanks for posting your query. Flank pain that almost makes you toss in the bed and blood in urine point towards a renal stone. Not all stones show up and you could very well have passed it. It doesn t seem to me that your hysterectomy has got anything to do with it. As considerable time has elapsed after surgery and flank pain doesn t relate to pain originating from pelvic organs, I m almost certain that it is not due to the surgery. It is very important that you maintain adequate hydration to prevent renal stones and your aim should be water intake as to keep your urine colourless. Do see a urologist who can assess if you are predisposed to certain kinds of renal stones and advice appropriate steps to prevent its recurrence. Hope this helped. Good luck!