What Causes Blood In Urine Of A Person With Permanent Colostomy?

I m a 38 year old woman. I m a stage 3 rectal cancer survivor. I now have a permanent colostomy after having my entire rectum removed. I also had my right leg groin lymph nodes completely removed. I m now suffering from daily chronic pain. All the sudden I ve noticed quite a bit of blood in my urine. I even have blood clots in my urine. I had a ua performed and no bacteria was present. So its not an Urinary tract infection. What could be causing this?