menses for about 15 days

hi....
i am having problem of irregular menstruation since my marriage in dec 2009.for first 3 to 4 mnths,i got periods after 20 days of due date.but from july i am having problem of early coming menses and days of bleeding are prolonged with light and dark bleeding.
i got infection in june which was treated by antibiotics.
i want to be pregnant but not succeeded yet.i am very much disturbed,
i got sex which was painful with my husband and got brown discharge for about three to four days.and then menses which was not due till 10 days and now its about 15 days i am menstruating with 5 days normal bleeding now having only clots.......plz help me out.
i have just started multivitamins.................