in these past few days, my brother has changed completely. He thinks that everything is a conspiracy theory against him. He says that everything is not a coincidence. he tells my mom to tell him the truth. He believes that me and my mom and everyone is working with some organization. i tried to explain to him that in social media data get sold and when you talk or search about something, you'll get later similar results in Facebook or Instagram because of data. But no, he still thinks this is a conspiracy. The bad part is he thinks he's right and everybody is wrong, he doesn't wanna go to the psychiatrist because he thinks him too is working with some organization. He looks at us like we're spies. Now he's telling us to tell him the truth or he's gonna harm himself. We don't know which truth he's talking about, and when we say that he starts laughing and saying "i knew it,you're all against me and you don't wanna say it"

Guys, please i need your advice on how to deal with this situation. i can't talk to him cuz like i said, everything I'll say is a conspiracy to him. What should i do ?