The worsening pain with movement, and not respiration, suggests a musculoskeletal cause or neurogenic cause, associated with nerve compression or inflammation. If nerve compression, it could be peripheral or at the nerve roots, where the nerves emerge from the bony spine. If inflammatory, the pain could be the first sign of herpes zoster, commonly called shingles.
Pain due to gallbladder disease often radiates up to the right shoulder blade. To my knowledge that is not influenced by sudden movement, as you describe, but it is possible that pain originating at the lower rib cage could radiate to your back.
You should definitely arrange to see your doctor to be examined and, at minimum, have a chest x-ray.
Hope this helps.
I'm no doctor, but I can almost guarantee you they will tell you this is musculoskeletal pain... you may possible need some images taken of you spine, but hopefully a chest xray to start