Hi.. The cause for the heavy and persistent menstrual bleed could be many.. It can include pregnancy, infection, stress, hormonal pills and many more.. The exact cause may be known only after seeing a doctor.. You can get an opinion from one of the gynaecologist available in this website, if you are interested in.. The link would be http://www.healthcaremagic.com/specialists/Gynecologist/Dr-Chetna-Jain/10