Hello and welcome to Healthcare Magic. Thanks for your query.
A sudden change in mood or behaviour, characterized by irritability, increased anger, aggression, etc. can be due to a few possibilities like:
1) Mood disorder
, like depression
2) Prodrome of a psychotic disorder
3) Organic personality change (due to a brain / neurological problem)
4) Severe stress
He needs a detailed psychological assessment by a psychiatrist
in order to arrive at a diagnosis. So, please take him to a psychiatrist for a detailed evaluation and further treatment.
Wish you all the best.
Dr. Jonas Sundarakumar