How To Deal With A Teenager With Possible ADHD?

Hi, I went through the quiz on this site for possible ADHD on behalf of my 14 yr old son and got a result that leans towards being a possible sufferer . The end statement suggests usually the symptoms must occur in at least two different settings . He has a history of certain symptoms, but really only displays them at school, so other than normal punishment which doesn t seem to work, what action should I be taking? Various punishments for his bad behavior at school have been put in place, such to the point I m about to deregister him from his local sports club, but I m worried that will be a bad decision.. In brief, I don t want to subject him to tablets that some kids have adverse emotional reactions to, what would an initial piece of advice be?