Could be subluxated rib. A Luxation is a full dislocation of a joint, so a subluxation is a offsetting of a joint that is less than a dislocation. The ribcage is the housing unit for your upper torso and its vesceral contents (ie heart, lungs, etc) and they separately attach to the sternum in the front and the vertebral bodies that make up the spine in the back. When a rib is subluxated the person may experience a sharp or dull painthat is not characterized as being in the middle of the spine, but further toward the lateral sides of the body usually occuring underneath the shoulderblades and may continue for a prolonged period of time.
As a rib pushed out the back it may injure the thoracic spine musculature which is why the most common symptom is dull or sharp pain that is irritated on movement possibly even upon inhalation. The back is not the only area affected as patients with a “rib out” will also feell palpatory tenderness on the corresponding rib at its attachment on the sternum.
If you get symptoms like this, see a chiropractor right away. It is usually a 1-3 visit type of injury and most patients feel instant relief after a rib adjustment. For fellow chiropractors upper ribs may involve the shoulder mechanism and/or sternoclavicular joint relating the problem to scalenes and overly tight pectoral muscles.