Sir. There are many reasons for having a chest pain- heart related diseases like myocardial infarction, valve prolapse, cardiomyopathy, or lumg related like pleuritis, pneumothorax,pneumonia or due muscle strain or gastritis etc. Since you are a young patient and based on your history I am assuming that you are a person who has a busy work life with lot of stress and you might be having untimely eating habits because of that, most of the times gastritis can present as heart burns where patient complains of chest pain, so if that's the case I kindly suggest you to follow a healthy well balanced diet, avoid coffee,tea,alcohol,smoking. Avoid spicy and oily food and avoid junk foods. Do yoga and meditation to destress. And as far as the pain in elbow is concerned it might be due to sleeping only in the left side by keeping your hand below the pillow, by avoiding such habit itself gives you relief. If the above suggestion doesn't apply to you, then the pain might be because of other causes, so consult a physician to ruleout those things.