Menstruation not stopping. The problem?

Please doctors this is my a year and three months of delivery of my twin through ivf ,after delivery my period was irregular but doctor placed me on hormone tablet i took for some time and it got better that was around February march My period was very okay...but sometimes it comes twice in a month beginning and the ending of the month, last month SEPTEMBER i got it first week then on the 29th it came mine is 5 days, it is supposed to have stopped yesterday i use like two pads in a day, no cramps, but today again is til coming and my period always comes with blood cloths, before i forget i had intercourse with my husband yesterday, night and my period is supposed to stop yesterday but then again is coming again today am very worried? I dont know what could be the problem??