Musculoskeletal strain: This is often the most common cause of pain between the shoulder blades, resulting from poor posture, muscle overuse, or injury. The pain is typically a dull ache and can be exacerbated by movement or certain positions.

Gastroesophageal reflux disease (GERD): GERD can cause referred pain between the shoulder blades due to the irritation of the esophagus. Symptoms often include heartburn and worsen with lying down or after eating.
Peptic ulcer disease: Similar to GERD, peptic ulcers can cause pain that radiates to the upper back, including between the shoulder blades, especially if the ulcer is located in the duodenum.
Thoracic spine issues: Conditions such as herniated discs, spinal stenosis, or osteoporosis in the thoracic spine can cause pain between the shoulder blades due to nerve compression or bone instability.
Costochondritis: Inflammation of the cartilage that connects the ribs to the sternum can cause sharp pains in the chest that may radiate to the back, including between the shoulder blades.

Myocardial infarction (heart attack): Although less common, myocardial infarction can present with pain between the shoulder blades, especially in women. It's crucial to consider this diagnosis, especially if accompanied by other symptoms like chest pain, shortness of breath, or nausea.
Pulmonary embolism: A blood clot in the lungs can cause sudden, severe pain that may be felt between the shoulder blades, often accompanied by difficulty breathing, cough, or fainting.
Aortic dissection: A tear in the aorta's inner layer can cause severe, tearing pain that may start in the chest and radiate to the back, including between the shoulder blades, and is a medical emergency.
Esophageal rupture: A tear in the esophagus can cause severe chest pain that may radiate to the back, including between the shoulder blades, often after forceful vomiting or other esophageal trauma.

Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain that may radiate to the back, including between the shoulder blades, though this is less common.
Sickle cell crisis: Individuals with sickle cell disease may experience episodes of severe pain, including in the back, due to sickling of red blood cells.
Tumors: Both benign and malignant tumors in the thoracic spine, esophagus, or other nearby structures can cause pain between the shoulder blades, though these are less common causes.
Infectious diseases: Certain infections, such as osteomyelitis (bone infection) or discitis (infection of the spinal discs), can cause pain between the shoulder blades, though these are relatively rare.