AF for 22 days

I had a miscarriage on 3/19/18 and the same day the doctor preformed a D&C.; Had a light bleeding for 3-5 days. My first AF after mc started on may 8th (8 weeks post mc) and it haven’t stopped, I told the secretary of my obgyn more than a week ago but gave me an appointment for the 29th. Have any of you experienced prolonged and very heavy menstruation? I feel very tired and it seems it won’t stop anytime soon. The blood is very red and with blood clots, I don’t know if this is something to be expected or I am experiencing something to be very concerned. Please help!