Helppp contractions?

It's 2am and I'm up. So at 9pm I had sex, instantly after I felt pressure and back ache but ignored it and went to bed.
I've been tossing and turning for hours with bad lower back pain but is sort of one sided on the right. My tummy is going rock solid with this. And honestly the back pain is coming a going.
What shall I do?! I can't sleep