By what you are describing it sounds like he could be suffering from paranoid schizophrenia or drug induced psychosis. I am no doctor or professional but i have experienced a similar situation with my brother. He was eventually diagnosed with paranoid schizophrenia, at the age of 20, after years of strange behaviours and episodes. He thought that the whole town was after him and out to get him. After a very serious incident he was sectioned and now he is on life long medication and living a normal life. He too abused drugs but we will never be sure if he was born with this illness or if it was the drugs. I beleive it was not the latter.
What I do want to tell you is that this country has a very poor attitude towards mental health and you will have to fight very hard to get him help. Please do not give up. Keep seeking advice from your gp and push for him to be referred to a mental health service in your area. There is help out there but it won’t come easy.
