You should be concerned as you have been smoking
for the past 20 years.
There is a high chance of you having COPD and hence a lung function test is inevitable and very important to know the status of your lungs.
I dont know why steroids
was started for you at the first place if you had pneumonia
as it causes more harm then help there.
Staroids and spiriva
will be good to use for COPD however it will be only decided on your Lung function