How is your son's social life? Is your son overall a happy teen ager? There may be underlying causes for his displeasure in activities. How are his grades in school? You need to have an open and honest discussion with him to see what is really bothering him lately. If refuses to open up to you, then you might want to try a neutral source like a counselor for him. You may also want to seek counseling for yourself as well if the situation does not improve just so that you can seek coping and intervention strategies in dealing with such teen age issues.
I hope that this had helped.
PLease ACCEPT. Thank you for your time. Have a wonderful day.