This is Dr. David
I am sorry about your son.
the only way to get him to get professional help is to section him into a facility to get medication treatment
if he is not willing to realize he has a paranoid personality disorder.
it sounds like he could have more than that.
he could have schizophrenia possibly
3 days ago he damaged many things in his mum's house, now he is with me I don't know what to do, where to help?
you need to call up MIND mental help hotline
and they can help you get resources to him.
and talk about options
he might be best to be placed into a mental illness facility for more intense treatment if it is a danger to you or himself.
it sounds like he is a danger to himself.
do they really help? or they refer to somewhere else?