What Causes Sharp Pain In The Shoulder Upon Coughing?

I have had an upper respiratory infection for weeks, have had two antibiotic shots, steroid shot, breathing treatment, and I am using an inhaler, went Tuesday back to Dr. had chest xray everything was ok, but I have a sharp sharp pain in my right shoulder pain when I sneeze like a knife is being stuck all the way in from back to front, it is worse since my dr. visit and I don't want to sneeze or cough, and it hurt trying to sleep the other night?