Your cough may be due to asthma, but I would not assume that's the problem without further testing for asthma. Some chest x-ray findings may be suggestive of COPD, but they are not specific. A chest x-ray is not the way to tell if someone has COPD. In addition the chest x-ray with uncontrolled asthma, may mimic the findings of COPD. Yes, the cough could be due to Mono. The mucus and voice raspiness suggests laryngitis. This can sometimes be seen with reflux of liquid and/or food from the stomach that then drops onto the vocal cords along with heartburn usually. Mucus from postnasal drip could be another cause. If the cough is really lessening, give it more time to go away.
Rest assured, if your pulmonary function tests were normal, you definitely do not have COPD.
X-rays are NOT considered a good way of diagnosing COPD. The pulmonary function test you had is a MUCH better way of figuring out whether you have any CHRONIC obstructive lung condition. Chronic cough can be a sign of poorly controlled asthma, allergies or gastric reflux.
A GOOD doctor can help you sort out among these options and help you get effective treatment. Spiriva is generally prescribed for COPD, but it is sometimes helpful for asthmatics (tho expensive). At this point, you may wish to consult a good allergist, who has experience in working with asthmatics to help pinpoint the cause & proper treatment for your continuing cough.
It does NOT sound like you have COPD.
Good luck!
Starion