Why Am I Having Heavy And Painful Period Twice In A Month?

hi, last two months i used to take contraceptive and i stopped and it was 9th day of my periods, without doctors prescription i had taken UNWANTED 72, on that the 3rd day i got bleeding and it was heavy and very painful and it last up to 8 days and by the 15 days again i got periods and the problem was same.. Because of the irregularity and hectic pain am really scared.. pls help me.