Side of my boob hurts?

So, for a couple of weeks, I've been sick and coughing alot. For a few days now, whenever I have a coughing fit, the side of my left boob hurts. It's as if someone jabbed me really hard near my boob or someone punched me from the inside slighty...I don't know how to explain it. But it's getting really uncomfortable and I'm worried. My boob looks normal. Is it bad? Did I pull something from coughing to much? Help...