Hi and welcome, Victoria!
Your symptom that feels like tissue being caught between your ribs sounds a lot like my gastritis. Ouch! I was diagnosed with it in 2011, and now only have occasional bouts with it, involving the upper part of my stomach. At its worst, it honestly felt like something was gnawing on me. Not fun!
Have you seen a gastro doctor and/or your regular doctor? It may be a good idea to have it checked out.
Yes, the neck, shoulder/upper back pain can be miserable. Moving around helps me, as well as a warm shower and/or a microwave-heated 'bed buddy.' Doing mild stretches, even shoulder shrugs, can help sometimes, too. And very gentle massage can feel so good when there's stiffness.
Hopes this helps a little and hope things are better soon! Best wishes.
"Never be in a hurry. Do everything quietly and in a calm spirit. Do not lose your inner peace for anything whatsoever, even if your whole world seems upset."
St. Francis De Sales