Hello thanks for asking from HCM for your health related queries I can understand your concern. You have symptoms like sharp pains in left upper corner of chest, nausea etc. These symptoms are getting aggravated especially when you think about your ex. So most likely the cause behind these chest pains is some psychological. Due to some underlying unconscious stress sometimes chest pain, nausea etc symptoms start occurring. This symptoms also point towards anxiety but more detailed history and evaluation is needed. Please visit a psychiatrist for help if these symptoms increase in severity or persist. You should get an Chest X ray done to rule out any respiratory cause though possibility is very unlikely. ECG can rule out any cardiac cause. For anxiety medicines like Propranolol when used on SOS basis provides relief from symptoms. Try to avoid thinking about your Ex because this is precipitating anxiety. Visit a psychiatrist for help. Thanks, Hope this helps you. Take care