I don’t think your problem is related to a breast
condition.Pain under your left breast
, could be due to several things. For example,Costochondritis, (chest wall inflammation) flatulence,ulcer,angina, pulled muscle,acid reflux, stomach inflammation etc...All these symptoms could very well cause the pain you are describing.
Therefore,,if I were you, I would consult a doctor as soon as possible to diagnose the underlying cause.