Is Cramps And Grey Clot During Periods Sign Of Miscarriage?

my daughter started her period yesterday and has been experiencing a lot of cramping. today she passed something that was grey with blood on it...about the size of a 50 cent piece, but flat in shape. she told me about it after she flushed it. she is doing fine, no heavy bleeding, just regular mensturel bleeding. could it have been a miscarraige?