I can tell you that after stomach surgery, and slow digestion issues, back and shoulder blade pain is a good indication that your stomach may not be emptying as it should. when this happens, it can impinge on a nerve that runs across your stomach and around your back to your spine. when this first happened to me, there was a drug on the market that instigated peristalsis of the flat stomach muscles and that worked wonders, but some years ago it was taken off the market by the FDA due to some side effects.