Not sure.. but it sounds to me like you are feeling run down from loosing so much blood so fast. Have you ever heard of Manorrhagia? Here is the description from my Obgyn's websight:
Menorrhagia
Heavy vaginal bleeding, known as menorrhagia, may be either prolonged menstrual flow (greater than 9 days) or excessive flow which may occur at the time of menstruation or in between periods. Most women not on hormones (such as birth control pills) during a normal menstrual cycle can go several hours without changing their pads. If your pad is saturated and needs to be changed every one to two hours, or you need to get up at night to change pads, you should consider this abnormal and have this evaluated by a physician.
Bleeding that occurs in between periods may also be due to abnormal conditions, although some women normally have a day or two of spotting midcycle during their time of ovulation. This may also be normally seen when starting birth control pills or changing to a different pill. You may also experience a change in bleeding patterns during times of increased stress. Under these benign circumstances, bleeding in between periods should not be persistent. If it occurs consistently, see your physician.
Any vaginal bleeding that occurs after menopause should be considered abnormal and needs to be investigated immediately.
There is actually a procedure that can be done to treat or help this. I am planning to have it done myself. Hope this helps.