Why Am I Spotting Instead If Having Normal Menses?

Hi doctor, i had my periods on 17th of august. The previous month also i had on 17th. But this time it started with spotting. And for alomst 12 to 13 days it was just spottings. Then it became a little more than mere spotting for 4 to 5 days. After that i started getting heavy flow. This flow almost continued till 14th of this month. Now it is reduced but not stopped. Its not even spotting but around medium to less flow. Its a month and 3 from the day of spotting now. Can u plz help and what can the cause be?