R.A.
I wouldn't have him drink Cocoa. Instead, try hot tea with lemon and honey. A humidifier for his room would be beneficial at night. I hate Nyquil, it just makes me feel worse and doesn't help my symptoms at all. Have him try Mucinex, or AlkaSeltzer Cold and Cough. If he has been coughing that bad for more then a week, I would take him to the Doctor's, especially if he isn't coughing up mucous. He could have an upper respiratory infection.