Contractions vs baby moving down

What's the difference between having a real contraction vs the pain you get when your baby moves deeper into your pelvis? I lost my MP on Saturday (after having a sweep on Thursday) and have had cramps ever since, but today they are coming and going in waves. Im not one to assume anything because I don't want to get my hopes up! I tried timing the cramps but they aren't always consistent but the pain is way worse then any Braxton hick I've experienced. It either starts in my lower abdomen or back and rotates around. 

Anyone have any idea??