I was wondering what are symptoms of "pulmonary fibrosis"?

Answered earlier. Early it causes desaturation with activity. Later it causes low oxygen tension in the blood, and later it causes co2 retention. So the symptoms will be air hunger and signs will be rapid breathing. At later stages there is cyanosis to nail beds, ear lobes and tip of the nose. Later as co2 accumulates there could be changes in mental status. If the o2 not corrected, it can cause heart attack.