My Granddaughter Is 20 Weeks Pregnant And Took Her First

my granddaughter is 20 weeks pregnant and took her first Makena injection last Thursday. she is having random shooting pains through her vagina and stomach. and is worrying about losing the baby. She has two uteruses and this is her second child. her first delivered at 36 weeks. The pain she is having is a new pain so she is wondering if it is from the shot or maybe something else or just normal. or if she needs to go to the ER.