could i have had a miscarriage?

im on the shot but i now that its not 100 percent and 3 weeks ago i had sex so i wouldnt be that far along, 2 weeks ago i started bleeding then about 2 days ago i had really bad abdominal pains that mad me almost fall on the floor crying, the blood has been dark red to brown and yesterday i passed a clot that was red, gray, and white that looked like tissue with a clear film over it, i was babysitting 7 kids so couldnt really get anything to put it in, and i was just wondering what others thought about it, if it could be a miscarriage, cause i never had anything like that ever come out of me that looked like that