What does it mean when you are on your period for two weeks and when it finally stops, three days later it randomly starts up again. it's never done this before.

Irregular periods: You probably have dysfunctional uterine bleeding . Your gyn can regulate your period with different methods such as bcp.

Vaginal bleeding: All abnormal vaginal bleeding should be professionally evaluated. That includes both abnormally prolonged periods and bleeding betwen periods, both of which you have had. There are many causes, many of them not serious -- but some potentially serious ones, including STDs, hormone problems, tumors (moslty benign), and others. See your gyn or other doc ASAP -- better safe than sorry. Good luck!