What Causes Pain Below Breast?

Hi. I have had a pain on the left side of my chest below my breast since I got over bronchitis a month ago. When I cough, sneeze, blow my nose, laugh too hard, lay on that side or even wear a bra, I have pain that is sharp. I have taken ibuprofen daily since then to reduce the pain. I cannot sit up from a laying down position without rolling toward my right side. I have had a pulled muscle on that side before but this pain is different. What could this be? Thank you.