Couple of questions about pneumonia?

I have been to my dr. actually 2 different drs. over the past 3 weeks. I have been sick since then. It started with an allergy attack which turned into a sinus infection, and now I have a constant wet cough. The last time I went to my dr. he listened to my chest and said it sounds clear whatever that means. I didn't have the wet cough then. I do now and I am coughing up mostly clear but sometimes green sputum. I am on mucinex DM also. I have a slight wheeze that comes and goes, no fever. My oxygen level at the dr. was 97-99, so is it possible that I could have pneumonia and the dr. not know? Is it more likely bronchitis from my sinus infection? I will be seeing the dr. again, but I am worried in the meantime that I may have pneumonia and not know it.