My mother has been on her period for 3 weeks she is 47 years old and has not been to the doctor is this something to worry about?

DUB: Well it is dysfunctional Uterine Bleeding (DUB) and should be worked up to determine why she is having this condition. Best wishes.

See a Specialist: Bleeding more than 7 days in anyone is not normal. At the age of 47, one most commonly sees conditions like a fibroid. She will need a biopsy done and n ultrasound. Please take her to see a gynecologist. Good Luck!