shadow on lung

I am very scared.  I had pneumonia 18 months ago and a chest x-ray showed a shadow on my lung.  I now have had a terrible cough (but not sick like I was with pneumonia) for 3 weeks now.  Dr. thought wooping cough or bronchitis and gave me a 5-day Z pack.  I finished it and am still coughing terribly.  I had a chest x-ray which showed a shadow that they think was the same one as before but now it is bigger.  I am getting a CT scan but am very nervous.  Can anyone advise me on what could be going on?  Should I be so scared right now or could this shadow that is bigger now be an inflamation (inflammation) of something?  Thanks!