Miscarriage or progesterone withdrawal?

Went to the doctor last Tuesday, no heartbeat about 7 weeks. I had been taking progesterone suppositories for a little over a week. I just stopped two days ago, woke up this morning spotting. No cramping or anything. Just wondering if this is the progesterone withdrawal or miscarriage starting. Anyone ever taken progesterone and had a miscarriage? How long after stopping the progesterone did you have the actual miscarriage? Thanks