Cant move when on back

So if I lay on the floor on my back I get a pain that feels so good lying still (stretching my back out feeling) but then I cant move...like the pain is so excruciating i cant roll over cant do a sit up to get up. I get bad back pain during the day as well (bern working 40+ hrs a week and working g for the first time in firever) it's at my tail bone pretty much and I got a prenatal massage and she was rubbing my upper back and could tell I had bad back pain but its getting to be a real problem