TLC reduced--what does it mean?

I had spirometry 5 months ago, after 2 bouts of bilateral pneumonia that nearly killed me. My TLC was 86%, at the time, which sounded great. I had a 2nd set of testing Monday, and the TLC was down to 72%. At times the pulmonologist has said I might have pulmonary fibrosis. I know there are a lot of different kinds of PF, and I'm sure he is just being cautious about giving the problem a name, but this is really worrying me--a 14 % drop in 5 months. All the other results were close to the same levels, and he said not to worry. He also stopped lowering my prednisone, for now. He has been weaning me down ever since October, and I am at 15 mg. a day. I'm using my oxygen more lately, and I have a cough. Do TLCs go back up, sometimes?
Thanks,
herdingcats