I've had my menstrual period for three weeks nonstop with huge blood clots?

See your doctor. If you do not use birth control, you may be pregnant. There me an ectopic pregnancy. At any rate you cannot figure it out on your own. See your doctor.
See your doctor. What you describe is very abnormal, and you should visit your doctor without delay.

Related Questions

I am having a very heavy menstral period and the blood has a very foul odor and I am passing very large blood clots. What could this mean?

Heavy periods. There are multiple options for heavy periods. Hormonal treatments such as birth control pills, Progesterone treatments and the Mirena (levonorgestrel) iud are effective reversible treatments that will help many people. There is also a drug called Lysteda that contains no hormones which will help others. Vaginal odor is usually bacterial vaginosis but confirmation will be required. Read more...

Why my periods got blood clots. I'm 29, period cycle normal. First time having clots and its big. There is no pain during menstual. Plz advice me. Thankz?

Normal variation. What you are experiencing is likely a normal variation in the bleeding pattern of periods. However, the presence of clots suggests more bleeding than usual and you may wish to get tested to exclude anemia. With or without testing, you may wish to take oral iron supplement to avoid anemia, Take the pills with meals and use a fiber laxative if you get constipated. Read more...

Severe cramps before during and after my period. Heavy menstrual flow and blood clots. Had an ultrasound but no cysts were found. What's the cause?

Menstrual pain. Ultrasoudn woudl find polyps, fibroids and ovarian cysts but may not see endometriosis which can be diagnosed on laproscopy. Would discuss the possibility with your OB. Read more...
Many causes. Most common causes are bleeding due to lack of ovulation (anovulatory bleeding), adenomyosis (where the uterine lining is misplaced and located in the uterine muscle), fibroids (a common benign tumor of the uterus), increased thickness of the uterine lining, a polyp and cancer. A biopsy of the lining should be performed, or a sonohysterogram (type of specialized ultrasound). Read more...