Thanks for your question on Health Care Magic. I can understand your concern. Since you have been to the doctor and he said that your lungs and heart are normal, no need to worry for major diseases. Sometimes stress and anxiety related GERD (gastroesophageal reflux disease) can also cause similar kind of left sided chest pain. So better to avoid stress and tension. Be relax and calm. Consult psychiatrist and get done counseling sessions, try to identify stressor in your life and start working on its solution. Take proton pump inhibitors for GERD. Avoid hot and spicy food. Quit smoking and alcohol if you have these habits. Don t worry, you will be alright. Hope I have solved your query. Wish you good health. Thanks.