Methylergonovine Late-term Miscarriage/Pre-term Stillbirth

Rebeckah
I had my son naturally at almost 17 weeks, due to IC, and at my post appointment my doc prescribed 

Methylergonovine

For all of the left over "fluff" in my uterus. Only thing is, I'm pretty sure it didn't work. 
Doc said he wanted me to pass some fist-sized clots and I was going to be in a lot of pain: but other than some mild discomfort and small, period-sized clots, nothing happened.
I read some real horror stories about people taking this med so I don't think it worked. I REALLY do NOT want a D&C.. Has anyone else had this experience? If so, what happened?