I'd try to change sleeping postures, use pillows to prop or to help keep you flat with arms to the side of the body and see if the makes for improvement.

A 3" memory foam mattress topper might reduce pressure on your shoulders , as well as a pillow that keeps neck alignment.
I found the 2" toppers did not cushion quite enough for my shoulder or hip pressures.

Gentle range of motion - leaning over to the side and letting arm dangle while doing slow rotations/swinging is a good one.