31 1/2 weeks lower back pain possible labor?

This is our first successful pregnancy. Our first ended in miscarriage and I'm 31 1/2 weeks. I've had really bad lower back pain and side pain. It's been going on for about an hour now. For the most part it's been pretty constant. I called L&D and they told me to drink some water, take 3 Tylenol, and get in a warm bath for about an hour. If it got worse before it got better call them back. 🤷‍♀️ I have some cramping and tightness in the front and baby girl is moving like crazy as usual but I've heard it should be the opposite? I also feel like I have to pee but I know if I try I won't be able to go I basically just feel the pressure or urge, if that makes sense. Could it just be really bad Braxton Hick's? What was your experience?