Fasting after miscarriage while bleeding

I got early stage miscarriage (6weeks) without fetus. So far it's happened more than 20 days. I am still got spotting blood daily. I would like to know am I allowed to do fasting & prayers? If the answer is yes, may in know what's the different between menstrual bleeding and miscarriage bleeding? And why during menstruation is not able to fasting but miscarriage is no problems. Thank you for your time.