Depo-Provera severe cramps and dark brown/red menstral

I received the Depo-Provera shot on October 31 for the first time. I had unprotected sex on November 19, 20, 21. My partner did ejaculate inside of me. On the 23 I was having severe cramps and dark brown/red menstral blood. When I went to go to the bathroom I noticed a mass laying on my pad, it was about the size of a silver dollar, skin colored and bloody. Since then I have had dark brown spotting. Did I have a miscarriage already? Am I pregnant?