Bad pain on lower left hip/pelvis

So last night I woke up to this awful pain in my groin area. I'm 20 weeks.. It felt like I was getting stabbed with a knife!!!! I see the doctor tomorrow... But when I talked to my mom she told me it may be stretching. But it hurt sooo bad!!! Has anyone had this? I wish I could explain it in more detail but it wasn't quite on my hip; more like lower left side. But super painful!!!!!