Mass or Infection?

A CT scan revealed a 2.6x1.3x5 CM somewhat elongated soft tissue density with spiculated borders at the Medial left lung base.  I went to pulmonologist and was given steroids, Advair, Levaquin and Mucinex to take for 2 weeks.
I am scheduled for a follow up HRCT of lungs only (first CT was abdominal but part of my lungs showed up) on Dec 1st.  Not scheduled to go back to Pulm. until Dec 8th and can only get in with the Dr's assistant.  I am going crazy with concern.  Is it possible for the CT results to actually be an infection even though it appears as a quite large mass?
Don't want to jump to conclusions, but getting scared.
Thanks!