Pain in lower belly and back

Im 27 weeks and 4 days. Ive been in pain everyonce and a while. And i dont know whats causing it. Ive had a baby before so i know what labor feels like but last night i woke up with my stomach hurting. I got up to go pee and felt the baby move down a bit and suddenly im having so much pain in my lower stomach and back i can barely move. I went to lay down and moving my legs hurt. I was shaking and crying because of how much pain i was in. I had such a hard time walking to the bathroom while my hubby started a hot bath for me. The bath seemed to help a bit. But if i was on my side it hurt again. Why am i hurting like this? Ive never had this kind of pain before.