Boyfriend Suffers from PPD

My boyfriend I feel is suffering from PPD. one day he says he will see a doctor. And the next day he will accuse me off working for the benefits agency and that he knows I am a liar and he is smarter than me!! He was being followed and then he accuses me left right and centre. I love him with all of my heart and soul but I cannot get through to him how do I deal with this? He is saying right now that he is being followed and I have caused this. He doesn't believe anything I say. I wish the old rules were in place to have him sectioned. But they are not. I want to help him but don't know what I can do.