Canuck1973, welcome. I have not had this problem but, I have close experience through my wife and other friends. For openers, almost 30 years ago she was passing blood to where did all of your tests including a retro grade pylogram that looks further up into the kidneys. We never found a cause, and her hematuria also subsided. I also have had two other friends that intermittently pass blood over a longer period with no known reason. Beyond kidneys stones, UTI, weak arteries in the affected area there are a host of other reasons. Some long distance runners and bikers get this. Sorry this isn't more definitive but, sometimes is does happen.
