5 Brain Tumors, Lymphnode Cancer & Lung Cancer?

Sounds like you have whatever viral infection that affected your mother. Your smoking probably makes it affect you more. It is highly unlikely you would have developed lung cancer at this stage but the longer you smoke the more likely it is to occur.

Starting at such a young age, while your lungs are still developing, puts you at greater risk. Take this as a warning and quit today.

I highly doubt it's cancer. I have smoked since I was 14 (21 now) and I'm perfectly fine except for asthma. It's probably a muscle, but to be safe you need to go to the doctor.

If you're concerned. About your family finding out, try and go (or at least call) your local health center. They are usually free.