My dad recently got sick, and he refuses to go to the doctor. All night he's been coughing long as if his lungs are going to pop out. It's a dry hacking cough , if that helps. He says he feels a little sick but it's mostly the cough. He's a smoker and when he coughs I get really scared that he's runing out of air or something. We were told his lungs were a little old for his safe however he should be fine. So what could it be! Please advise