See a Dr. Abnormal bleeding can certainly be caused by benign or malignant tumors. It can also be caused by pituitary malfunction...And don't forget the possibility of an ectopic prenancy. This is life threatening, and should be ruled out first.
Abnormal gyn bleed. Hypermenorrhea - abnormally heavy or prolonged menstruation; can be a symptom of uterine tumors and can lead to anemia if prolonged. You may want to consult your primary phyician or gynecologist.