Did anyone's labor start with back pain?

Hi everyone! I am 39+2 and had a membrane sweep yesterday morning. It has been about 36 hours since the sweep. I walked all day after the sweep but had nothing more than a few Braxton hicks. Had sex around 9:00pm tonight and had contractions and back pain almost immediately. The contractions aren't quite regular, but they're excruciating and the lower back pain feels like the worst menstrul cramp ever. I don't want to call the hospital yet just in case it's nothing but I feel like I'm in a lot more pain than usual. Did anyone else's labor start with excruciating back pain? Thanks in advance!