I Hurt Really Bad Under My Left Breast, Almost Feels

I hurt really bad under my left breast, almost feels like a cracked rib or something, hard to take breaths at times. It has gotten worse over a few days now. I haven't done anything out of the ordinary or have had any injury to the area. No bruising there either. I have been taking a lot of advil and ice doesn't help. Any suggestions on what may causing this pain?