Dear patient , chest pain can be due to some problem related to chest wall strectures (including skin, breast and musculoskeletal structures), lungs and pleura (covering around lungs), medistinum (connective tissue in side chest wall) and structures with in it, heart and its covering called pericardium, or may be referred from spine (thoracic and cervical spine) , brachial plexus (a nerve plexus in neck) and abdominal structures ( including stomach, esophagus, gallbladder and liver,and pancrease. Cause of pain could be infection and inflammation in these structures, trauma, vascular event, neoplastic process, degenerative process etc As you say that your left breast is numb , i want to know that is there any rash over skin on your back or chest , any breast lump or nipple discharge, neck pain , restriction of neck movements, and what is the quality of pain . your pain seems to be due to brachialgia which is a neuritic pain due to irritation of nerves in brachial plexus. As your tests for heart are normal , you should also try to rule out any problem with your lungs, abdominal structures and spine by getting Chest X-RAY, Cervical Spine X-RAY, and USG Abdomen done. Mean while you can try the following medications tab gabapentin + methylcobalamine(gabaneuron) at bed time capciacin ointment(neuro cream) for local application over chest Tab tremadol 50 mg as and when required please do not try to drive vehicles or machinary while you are taking these medicines because they cause some seddation. also make sure that you are not pregnant or lactating a baby