... I am still having my period.

I was given three packs and told to skip the pink pills and start a new pack immediately because we wanted to limit my periods to every 3 mo. because I have really painful cramps and headaches. During the 4th week on white pills I began my period. It is now the 6th week and I am still bleeding. Is this just my body adjusting to the new birth control pack, or should I seek medical assistance?