Hello!
I understand your concern. These behaviours could be because of a mood disorder or could be emerging from a life-altering event. You can take him to a mental health professional. A psychiatrist can provide medication but he will need therapies too. So you can even consult a psychotherapist/Hypnotherapist/NLP practitioner. If needed, you can even admit him in a mental health hospital, but you can consult the psychiatrist/psychologist/psychotherapist about the same.
Next Steps
1. Visit a mental health professional
2. As friend/family, be there for him. Tell him that constantly that you're there for him to help him through everything he's facing. Family and friend's support makes the journey slightly better
Health Tips
ensure that he doesn't intake alcohol/drugs. don't force him to do things he doesn't want to do