There is a possibility that you have the after effects of a pulmonary infection related to mold or fungal spores. I thought I might be able to help when I read about your symptoms that are very similar to mine. I can tell you from my personal experience that I was diagnoised with a condition called coccidioidomycosis or Valley Fever. It's a fungus spore prevelant in the southwest U.S. and parts of Mexico. In the Midwest, there is a fungus that causes a condition called histoplasmosis. The research I have done shows that these and other fungi can cause respiratory issues like chest pain, congestion, cough, lung scarring, and even masses in the lungs. Your additional symptoms of night sweats is also very common with these infections. I don't know if this helps or not, but I hope you will keep us updated.
Happy Easter
This problem is probably not primarily due to smoking 4 cigarettes a day. The scaring can be from past problems which were aggravated by earlier, heavier smoking. The current problem either is an acute one from an infection, or the result of smoking in the past. It may be from past respiratory infections, such as Chronic Bronchitis. In either case, I would suggest seeing a Pulmonologist to discuss these problems and get a treatment plan in place.
Of course you already know that smoking is a bad idea. What you may not realiza, is that when you smoke, you kill the villi in your lungs. Villi are responsible for pushing mucous out of your lungs. By smoking, you increase your recovery time, and you risk of continued infections.