Hi there, Ive been struggling with the same issue. Had all the tests and nothing ever shows up. For me seems to happen every 2 months. It just happened to me again today, last time was February. It’s so strange. I was going to call the dr after rethinking I’ll see how things go if it settles gets worse and give him a call Monday. Last time I spoke with the urologist he said I might just be one of those people that have blood in their urine. It’s certainly unsettling for sure