IMPORTANT: If you are having abnormal bleeding, the place to turn is a trained medical professional- a nurse or a doctor- not a website!
Simply: vaginal bleeding that is not supposed to be happening. It can be a result of stress, but even that is something you should discuss with your doctor. The most common symptom of uterine fibroids, although it may be an indicator of other conditions and more serious complications, that include heavy or prolonged bleeding duringregular menstruation or bleeding in between periods. - Uterine Fibroid Tumors
You can find more information on causes of Abnormal Bleeding here: http://www.gynalternatives.com/abnormal_uterine_bleeding.htm