It is likely that the problems you're facing is due to hormonal imbalance, if the bleeding is heavy with clots, I would advise you to visit a gynecologist so that you can be examined and undergo investigation such as ultrasound to rule out any residual contents and have it treated accordingly. Keep yourself well hydrated and well nourished during this time as this time as the blood loss can cause weakness. You may require an antifibrinolytic. If the problem persists or worsens visit the gynecologist at the earliest.

This could be due to harmonal variation after still birth , it could also be due to retained products ,after how many weeks you had your first periods ? It needs detailed history and examination ,consult gynaecologist