advice?

Lucky • Antonio James 6lbz 8 oz 10.17.15 Joshua Michael 8lbs 6oz 08.05.18 both at 38 weeks 5 days. My children are my ♡♡♡♡ Princess Zarya 5.3.21

so im 36 weeks today. im on baby#2 but my first didnt feel this way. im having alot of cramping, back pain n pelvic pain. it hurts to sit down at first. it hurts when im laying down like my pelvic bone it feels like hes tryna come out almost. should i call the birthing center cuz i cant ever get ahold of my doctor. p.s i went at 38.5 weeks with my first son