What would cause burning pain on the very edge of my breast near sternum? the pain comes and goes, sometimes for months.small area and heart flutters

Checked with doctor?: Your symptoms are consistent with anything from anxiousness to acid reflux from the stomach, to hyperthyroidism or even atypical acute coronary syndrome, to name just a few things that come to mind. I see you are in fact on levothyroxine. Last time your blood levels were checked on your t4/tsh? You may benefit from a little dose adjustment. Make an appointment to see your doctor. Good luck.