Have they given you an ultrasound? Don't get worked up thinking you have cancer. But from whay you are saying it seems there is some problem going on here that needs to be further looked into.
I had problems similar a few years ago. I went to doctor after doctor and finally one felt something on my exam. He told me he felt a mass and ordered an ultrasound. Turned out to be a large cyst on one of my ovaries. He told me he will do surgery and during surgery after he gets it out he will send to pathology and if it was cancerous he would remove my uterus and if no cancer he woud just close me back up.
I was lucky, it was just a cyst with no cancer.
Just keep looking around till you find a doctor who will look into this pain and bleeding. It took me a few years to find one who listened and did an extra good exam to find my problem.