What causes 5 second stabbing pains in left chest near center of the breast at the breast line? PCP says not cardiac. Nonexertional. Cant reproduce pain

Is it ongoing. Sometimes we can only rule out the serious causes of chest pain such as heart attack or blood clot and cannot explain otherwise why you have it. If it has resolved you shouldn't worry about it. If it is ongoing you could consider pericarditis (inflammation of the heart sac) which could give you stabbing chest pains. See dr again if pain persists.