Chest pain on left side when i lay in certain positions for a while ?

See Your Doctor: While this does not sound like a heart attack, blood clot in the lung, tear of the aorta or collapsed lung, it is worth a visit to your doctor. Probably a musculoskeletal problem and can be managed conservatively. Any shortness of breath? If you develop other symptoms and it occurs without your having to lay in certain positions, consider a visit to the ER. Liver/spleen disease? See your doc!