Periods form last 17 days. Reply asap.

My friend is having periods from last 17 days, as she took an ipill on day 12 of her menstrual cycle after having intercourse with her husband. Her periods were delayed for about 10 days which is a normal side effect of taking ipill, but in the starting of her periods, there were hardly few traces of blood after 4 days her blood flow increased and today is her 17th day of period and she is having cycles of low abdominal pain. We searched that imbalance of period is normal after ipill but 17 days period is not a normal side-effect. Please tell us some measures or treatment and also the reason behind this as her periods are not stoping. She is 21 year old and a healthy girl but her haemoglobin is low. Please tell us what we can do. Please reply asap.