Upper Back pain and sleeping on back

This is my second pregnancy (I’m 21 weeks) and I was afraid my upper back pain would come back. And it has-badly. Mainly at night. It got so bad that I couldn’t sleep at all. I have finally found that a rolled up and folded in half blanket stuffed under my mid to upper back is the only way to ease the pain enough to sleep. However, they say it’s bad to sleep on your back... anyone have any suggestions on how to ease the pain without sleeping on my back? Or is sleeping on my back okay for now? I just want a good nights sleep 😞