Could this be cancer? i sometimes bleed from my vagina when i have a bowel movement.

This : This is not normal and warrants a medical evaluation as soon as possible. Cancer is possible. If there is a tumor it could cause abnormal bleeding. There could also be other things going on, fibroids, infection, etc. You need a complete physical and work up. Good luck.

Vaginal bleeding: You need to be evaluated by a board certified ob/gyn. This is very unusual.