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Please help my understanding of Subtitles which is originally in a video.?

"SUBTITLES" BCAB "We'd Like Change Your Mind" Television Campaign [2003] Source (video) http://www.bcss.org/Get_Information/Newsroom/public_service_announcements.html# --- in the video Male friend: So what are they saying? Patient : They said I have schizophrenia. 　　 Male friend You mean like a split personality. ( You mean, like in the movies?) Patient: No it is not that at all. Female friend: Is it treatable? (Are you crazy?)　　　　　　　 Patient: Yeah ,I am doing good　① Male friend Well, then we’re glad. (This　② scares me.) Patient Are you sure OK with this.③ 　 Female friend : Hey, we’ re still your friend (Stay away from my family.)　　　　　　　　　　　 ( )= subtitles. My question is as below ①　what “I am doing good” mean? Is it correct that this mean is that that the patient am receiving good treatment by doctor? (How meaning is different between I am doing well, and I am doing good.?) My Question ②　This scares me. What does “This” points? about the patient doing good? Or the things that he believes that his illness is treatable. Or about the fact that Patient has schizophrenia? My question ③　What does “this ” points ? It becomes that They have a friend who has schizophrenia? Thank you for your cooperation. (English is my second language (non-native English speaker and my doing this as my hobby. )

Public Comments

1. The phrase "I am doing good" is more of a personal statement than about quality of treatment. There is no difference between saying 'I am doing good' or saying 'I am doing well' but 'I am doing good' is an Americanized(I may have made this word up) phrase.
2. 1. "I am doing good" means overall how he feels 2. "this" refers to the situation (schizophrenia) 3. same answer as #2 above