Hi I'm new to reddit, I just made this account to ask for help. I'm not sure where else to turn and I've always found helpful information of these forums. My sister's boyfriend is having severe mental health issues and we don't know what to do. They have been together about 7 years and he is part of the family. He has been the absolute best the entire time we've known him but in the past 6 months or so he has been showing signs of paranoia, delusion, and hostility. As of right now he is not in danger of hurting himself or others. Out of nowhere he started having episodes where he accuses everyone around him of hating him, manipulating him, and having all around negative ulterior motives. When it occurs he sounds and acts like a totally different person and it's frightening. It is a night and day difference between those episodes and how he normally is. In an episode, he rants and rants and is nearly incoherent, and he won't listen to reason. He becomes completely irrational. Not to diagnose him, but from our research he shows symptoms similar to psychosis, bipolar disorder, or schizophrenia. We had him see a therapist but it wasn't a good match and triggered him further. He found out the therapist was a former police officer, which triggered him because he has al ways had a fear of the police. He went so  far as to say the therapist might have sent someone to his work to spy on him. We have also had him reach out to his dad, but we are afraid that his dad isn't getting the full picture because he doesn't live here and hasn't seen him have an episode. We are afraid to talk to his dad behind his back,  or stage an intervention, because it will trigger him even more and we don't know if it's necessary yet. An intervention would be the last resort. 

Tl;dr: my family member is having a mental breakdown involving severe paranoia, among things.I can provide more information if it helps. If anyone has any advice or information, or has been in a similar situation, any advice would be a huge help. Thanks!!