Suggest Ways To Manage Someone With Anger Management Issues

i have a twenty one year old son that has an anger issue. this started about 6 months ago when he started a new job and was diagnose with an STD. no he has told me that he gets angry because he thinks people are talking about him and he thinks something happen to him when he was young all of the these are false what is wrong with him could it be stress or chemical imbalance of some kind