How badly can your lungs deteriorate?

after smoking about half a pack of camel filters for almost 2 years? I actually smoked full pack of malboro lights for 10 years and then I quit cold turkey for 6 years after having some weird allergic symptoms that the doctors couldnt figure out. After no symptoms for years, I decided to start back up due to stress at work about 2 years ago. Now my allergies seem to have come back and my nose is constantly dry and congested. To make matters worse my chest feel congested and having difficulty breathing. I thought my lungs were healed when i quit for 6 years but i guess not. How much damage do u think ive done in the past 2 years?