There may be a prominent change in the way he behaves with his friends, his siblings or his parents.
For this, it is very important to know your son well.
Having one to one conversation with your son may prove to be of great help.
Be patient with him, don't push him or nag him too hard.
Be gentle and kind and show him that he means a lot to you and that you are proud of him.
The problem for those who wish to help is that, on the outside, a boy who is having problems may seem cheerful and resilient, while keeping inner the feelings of being troubled, lonely, afraid, and desperate, hidden.