Hidden pain in the left scapula can be caused by excessive exercise, scapular disease, heart disease, myofasciitis, lung disease and so on. 1. Excessive exercise: Excessive exercise of the upper limbs or back muscle exercise can lead to the accumulation of lactic acid in the muscles of the scapula, causing physiological pain, which can be relieved after rest. 2. Scapular disease: bone and soft tissue injury at the scapula caused by trauma, or primary tumor and bone metastasis tumor occurring at the scapula will cause pain symptoms at the left scapula. 3. Heart disease: heart attack, angina pectoris and other diseases can cause radiating pain in the left scapula, and it is necessary to carry out blood test to check the cardiopulmonary function, electrocardiogram, angiography and other tests to make a clear diagnosis. 4. Myofasciitis: Myofasciitis can occur when the soft tissues around the scapula are strained or cooled for a long period of time, and aseptic inflammation can occur locally, resulting in pain and other discomforts in the left scapula. 5. Lung diseases: tumors, tuberculosis, inflammation and other diseases occurring in the left side of the lungs can lead to pain in the left scapula of the back. There are other causes of left shoulder blade pain, such as trauma. If the pain is not relieved after resting, it is recommended to go to the hospital in time, complete the relevant examinations, clarify the cause of the disease and then follow the doctor’s instructions to carry out targeted treatment, which will help to alleviate the pain and other uncomfortable symptoms as soon as possible.