27 wks 3 days and bleeding???

Redd77
I was diagnosed with placenta previa in my earlier weeks last US the doc said it shifted. This morning at 27wks and 3 days I woke up to blood?? I don't know if I'm just worried cuz I saw the blood or if I'm really feeling these cramps. Not alot of blood n my cramps are like a period. Any guidance or suggestions needed... I'm going to call my doc in an hour.