Shoulder blade pain can have many different causes. Although you may assume you sustained an injury or simply slept in the wrong way, the pain might actually be related to your heart, lungs, spine, abdomen, or pelvis. In cases like these, the pain may be referred, meaning that a problem in one part of the body excites nerves that trigger pain in another part of the body, such as your shoulder blade.
Source : Verywell health
