Lay on your back... get a pillow and put it under your left or right side to ease pressure off your back... you could also get three pillows not includinh the one got your head... place one under your lower back, under your knees, and under your feet.
Try a bath warm with some epsom salts, if you can get as much pressure off your back the better.
Hope this helps!
I would go to the hospital if it gets bad. Try to take it easy and Google things that will give u relief