I have RSD and back/neck problems so I'm familiar with your issue. Since I spend all day every day laying in bed I bought the mattress genie. It makes your bed into an adjustable bed. I inflate it every morning.

Besides that....I have to put my 3 pillows vertically otherwise my lower back as no support. Getting a back brace, even a cheap one, would keep your back straight. I have horrible posture with my neck when laying down. I'm tall and my head doesn't have anything to rest in. It's passed the top of the pillow. That's why my neck hurts plus the arthritis.

You just have to train yourself, in a way, to keep your back and neck in the correct place. I used to play the piano so I've always had good back posture. When I'm not laying down...I had to train my neck to be in the right place.

Hope you feel better really soon!
Heather