Back labor, ligament Pain, baby moving lower??

I'm 36 w 1 d and I'm having horrible sharp cramping down low in my stomach and into my back. They feel like their deep and they come and go. I'm not sure if they're back contractions or if I have some pulled ligaments. I have been sick and blowing my nose a lot so it wouldn't suprised me if its that or if my baby is moving lower, although he's already almost completely engaged. Any thoughts?