Went outside in cold weather, next day my back became sore, and every time i breath my left chest hurts, what's wrong?

Cold exposure: This may be a form of "pleurisy" or early bronchitis - either diagnosis is associated with inflammation of the airways and can be exacerbated by cold air exposure. People who smoke are most susceptible to these types of symptoms. Limit exposure to extreme temperatures and avoid smoking. If symptoms persist or worsen(especially fever or productive cough) I would pursue a formal evaluation with M.D.