What Causes Recurrent Periods In Women?

Hi i am a lady aged 20yrs with a weight of 60kgs.i av been havin pain durin sexual intercourse which also caused bleeding in my vagina.this was happening when i was with my ex-boyfriend..i now have a new boyfriend and this does not happen now.i was using depro vera contraceptive but i stopped 2months ago although i have noted that my periods are coming 2-3times a month and are usually taking a long period of around 8-10 days.wat might be the problem?