It sounds like a cold virus, but you could have Mycoplasma or Chlamydia
pneumonia? You can have some tightness with that and low grade or
no fever. Usually, you have a dry
cough and sometimes can have pain in the rib area and dry cough. It lasts about 1-2 months and usually follows a cold or flu. Sometimes it is resistant to some antibiotics. But it often goes away on its own. They call it "walking pneumonia." Did your CT come back yet?