Worried first time mama to be!

I'm sure this will be another post where I'm reassured all is well but I just can't stop stressing about this! Last night I sat up quickly after my cat knocked something down and it woke me up. As I sat up, I heard a snapping sound in my lower belly and then had some cramping. Half asleep, I chalked it up to being my back cracking but now I'm worrying. Baby has been moving, but just barely. He isn't nearly as active as usual and I've been having some fairly painful stomach and hip pain. Should I be worried? Or should the fact that he's moving at all be enough to calm me down? I just drank a slushy to try and get him moving a lot (typically he has a little dance party when I drink them) but it hasn't made a difference at all :(