Hello dear, its heartening to see your concern for your cousin. You are definitely right that he might be suffering from some mental health issue. Howsoever, it will only be possible to make a correct diagnosis after interviewing him in detail. You can try to convince him to seek counseling by a psychologist by communicating the recent changes in his behavior in an empathic and non judgemental manner and relating that seeking support can help him to get back at being his usual self again. Sometimes, families can be quite judgemental about such situations(young son not working, sitting at home, spending money etc) and express hostility openly; this however will further push him away from sharing his problems with them...so if such is happening, it needs to be regulated as a positive and motivating environment can push him to make positive changes. Consultations are also available via online chats, so you might seek them if he is apprehensive to go out. Hope this helps, good luck!