Hello and hope you are doing well.
If you're worried the scar tissue, have lung function tests done, this will help assess if it has affected the lungs. This will also help assess if Asthma is under control. Light headedness could also be due cardiac disorders. Symptoms are usually aggravated with exercise in cardiac disorders. Again inadequate sleep, hypoglycemia, anemia and vitamin deficiencies can aggravate your symptoms of light headedness. Please discuss these options with your consulting doctor.
Hope this helped and do keep us posted.
Could be allergies, yes once you have had pneumonia you will have scarring ..it wont affect you, check out online for environmental allergies .