Good sleeping positions? 🤔

I've been waking up in the middle of the night and in the morning with a very tight stomach and painful lower back... I have rotated from side to side and sleep with a pillow between my knees and propping my stomach up to relieve pressure but the only thing that seems to help any is sitting up or laying on my back.. Has anyone else experienced this? I never had this problem when I was pregnant with my son.. could it be a positioning thing?