Hello. I Have Pain On The Left Hand Side, By

Hello. I have pain on the left hand side, by my back and below the rib cage. It hurts when I cough and take a very deep breath. The pain began about four days ago. At first I thought it was a pulled muscle, but it's obviously more than that now. About a month ago, I was sick with what I think was the flu. It went away after about 1.5-2 weeks, but I was left with a harsh cough that persisted until just recently. The cough is now mild. Normally only when I wake up and very rarely throughout the day.