I am not a doctor, but assuming that your periods are still happening regularly (28-31 days apart) you should be fine. Prolonged menstrual periods are not serious most of the time, unless you feel drowsy, then you should go see a doctor. Otherwise you should be fine.
How old are you? Can you be pregnant? If you are not pregnant and your age is below 35; aidan is right, otherwise mussadiq is right..