Did you go back to the clinic? Blood clots, is a sign of a miscarriage, byt i do hope for your sake you didn't or arent going to. They can't prevent it from happening. The shot they gave you maybe was because you are rh negative? I know this because I miscarried at 13 weeks. They do however need to make sure everything is out so you don't get an infection if you did miscarry. That happened to me.