The common causes of vague pain in the left rib cage include heart disease, stomach disease, pleural disease, lung disease and so on. 1. Heart disease: coronary heart disease, myocardial infarction and other heart diseases usually manifest as pain in the left side of the ribs, accompanied by chest tightness, panic, shortness of breath and other symptoms. 2. Gastric diseases: chronic gastritis, gastric ulcer and other gastric diseases will be manifested as pain in the left side of the ribs, and may be accompanied by loss of appetite, nausea, vomiting and other symptoms. 3. Pleural diseases: pleural diseases such as left-sided pleurisy can cause hidden pain in the left side of the ribs, and the pain is usually more obvious when breathing. 4. Lung diseases: Lung diseases such as left-sided lung infection and tuberculosis may also cause vague pain in the left side of the ribs, which is usually accompanied by coughing and sputum. Hidden pain in the left side of the rib cage may also be caused by other reasons, you should go to the hospital in time to find out the cause and targeted treatment.