What Causes Heavy Vaginal Bleeding After Taking Duphaston?

Hi. I m 26 years old with 58kg weight angle 5 3 height. My menstrual cycle got disturbed when I took Green Coffee Beans pills for reducing weight after preterm delivery. It s been 6 months now after my delivery. My periods were normal 2 months back but I got my period a week early this month. I was stressed as well. Moreover usually for 7 days I have normal flow of menstrual blood and it takes 3 more days with slight spotting. This time I took duphaston on 6th day as I was having cramps and brown blood flow was being discharged. On 6th day color changed to red but it was just spotting. It s now 7th 8th day now and I m having heavy blood flow. Is it okay?