Hi I Suffer Miscarriage On July 2014 After That My

Hi I suffer miscarriage on july 2014 after that my menstrual cycle is normal, but on october 2015 my period is not normal anymore it takes 15 to 18 days before it ends, begins with 5 days spotting 7 days heavy period and then 4-6 days spotting again then stop, I went to the hospital to check up with an OB then she told me to conduct ultrasound for us to be able to know what's the cause of the heavy periods and spotting, my OB noticed that I have an Ovarian Cyst with measure's 6.72 cm with thickened endometrium which measures 2 cm, she advised me to take duphaston 10mg Once a day after suffer, my period starts on may 18 until now my period won't stop with heavy periods after taking duphaston 10mg, is it normal that my period last for almost a month after taking duphaston 10mg once a day? Thank you.