I have a sharp stabbing pain under my left breast. just showed up random 3 hrs ago. hurts to take deep breaths. what could it be? no trama to area

A few choices: If this is a new , sudden pain , as you descibe, it could be spasm of the anterior chest muscles or intercostal (rib) muscles. Heat, stretching, and anti-inflammatory meds will help. If the pain radiates to the back, consider intercostal neuralgia (irritation of the nerve for each rib). The rib can also be restricted on breathing in and out (inhalation or exhalation), which would cause pain -.