I'm pregnant and I have really bad back pain! "what can I do? "

OMM. I would recommend seeking out a do who treats back pain with osteopathic manipulation. This is an excellent treatment that can be performed throughout the course of your pregnancy to provide you with relief as your baby grows.
Depends... ...On how far along you are. If you're close to your delivery date, it could mean you're in labor! (happened to me once during my internship.) call your obstetrician.