Thanks for the query.
Usually after undergoing abortion
the bleeding will subside after 7 to 10 days.
And spotting can continue for few more days.
As you are having continuous spotting for 20 days, better to get examined to rule out retained products.
So, once consult gynecologist, get examined and go for ultrasound
Ultrasound can find out the possibility of retained products and can also access the endometrial lining.
If there are no retained products, treatment with anti - fibrinolytic drugs help in decreasing the spotting.
If retained products are there, depending on the amount of the products you may need medical treatment or D&C.