My 19 year old daughter received her first Depo Provera shot for birth control two months ago. The first month she didn't have a period. The second month she started spotting and cramping. Her cramping became and then she passed a large mass which I believe was a blood clot. It was about 2 inches in diameter and and looked like a bloody mass of pink looking skin tissue. Her cramping subsided once she passed it. Is this normal or should I be concerned about this?