Could this be a miscarriage?

There really isn't anything here that we can tell you that would answer your questions the way you would like. There is a possibility that she is miscarrying, but the only one who can tell is the doctor. I would call him and let him know exactly what is happening. If the doctor is not available I would go to the ER and get their opinion. If she pes anything that looks like tissue (not just clotty blood) save it and take it with you to the hospital for a pathology test. Best of luck to you.