Took beige pills after completing menses, had mid-cycle bleeding that is continuing, intense cramps. Serious?

I ve had regular periods since I started when I was 13- they usually last roughly 3 days. I have been on the Contraceptive Pill , Levlen ED for almost a year and things have run smoothly all year with next to no complications. Over New Years, I missed 3 pills, as I was away and forgot to pack them. I had my period on the 4th of this month for the normal amount of time. I continued to take my pill as per usual.. But being on the beige pills (not the sugar pills) after I d finished my menstrual cycle, I had bleeding almost two weeks later- last Sunday. This frightened me, I ve searched and searched for answers. Five days later and it s still going heavier than usual. So not only has my period come over being on the contraceptive pill which should usually stop it from coming at all if I decide to skip it- but it has lasted longer than usual, it has been much, much heavier, and for the first time since I started having my period, I have had really awful cramps to the point where I end up in tears . Is there something I can do- or is there something wrong with me?