What Are The Symptoms Of Miscarriage?

I'm 14, and I think/know-ish I had a miscarriage. I recieve the depo shot every 3 months. I shouldn't get my period, but I did. I have had it for ten days. I always use tampons. Still am. I have had sex with my boyfriend a total of about four times. (all in a matter of two/three weeks). I had a sack thing come out of my area down there.. My mom wasn't sure what it was, so it's in a baggie in the freezer(gross, I know). But I looked up pictures of "Early Miscarriages" and it looked the same.. What do I need to do?