Hi, Twiggy! I suffered with back pain for years, and still do to some extent. I don't lay completely on top of the pillow. When I get in bed, I turn slowly on one side and then tuck the pillow under my back. This allows me to sleep on my side and partially on my back. If I sleep flat on my back I awake in terrible pain. Also, tucking the pillow like this allows you to keep your knees bent, if that is comfortable for you. That helps stretch those back muscles all night, which helps.
This is my first time on this board so I might be repeating something that has been addressed in the past, but, once I learned how to get in and out of bed, and in and out of my car correctly, my back pain has lessened greatly. I'll explain and I hope I'm not boring anyone!
To get into bed, I sit on the side of the bed, and slowly lay down on my side...keeping my knees bent all of the time. To get out of bed, I turn on my side, bend my knees so I'm in a sitting position and my legs are hanging over the side of the bed, and push myself up. Your legs will act as leverage and bring you to a sitting position without pulling your back muscles I bought a cane and keep that by the bed to use to push myself up. It's worked for me!
To get in the car, sit on the seat with your feet out the door. Then grab the steering wheel or the seat and swivel your legs in the car. Just reverse it to get out of the car. I always buy cars with leather seats because my back end slides on that easily. But, I've rented cars with cloth seats. So, when I get a car like that, I place a plastic garbage bag on the seat and cover it with a towel. This will allow you to swivel, kind of like a Lazy Susan!
I hope this helps someone!