Bright dark red blood days after miscarriage

peaches • Mom of 7, #8 miscarried was due May `19 rainbow baby due june 2020

Last Wednesday I had to take medicine to expel my baby since it was already gone from my body. Didn't really bleed except 1 small clot then light followed by 2 days of brown and then 3 days of medium/ light period like bleeding. Today is Sunday; 4 days later and I just went to the bathroom. Before doing anything, the minute I sat on the toilet I felt something big come out with a plunk in the toilet and i am bleeding heavy bright dark red blood. Idk what to do or if I should react by going to the hospital or wait to see if it gets heavier or just ignore it. I don't see the doctor again until the beginning of next month because when I went thursday he says I still had pregnancy symptoms in my urine. Could it be possible the other doctor was wrong when she said everything looked clear and nothing was left? Could that have been the sac??? I couldn't get to it to see what it was. Now I am cramping badly again.