So, I need my main character to by dying of some very serious illness. I'm currently thinking an aggressive inoperable brain tumor is probably a pretty safe choice. Or maybe some other nasty sort of cancer, I don't know. Thing is, I know very little about medicine - I write about sword fights and magic and stuff like that. Terminal diseases in particular are way outside of my comfort zone since I find the subject depressing and existentially terrifying. I've tried doing research on my own but I still don't feel like I know what I'm doing here. So at this point I'm kinda looking for whatever advice I can get. Some context for what I'm going for: -The story starts out on modern day Earth in an unspecified western country. My protagonist is a girl, mid to upper teens, who has been physically active in the past but has since fallen ill. -The illness is incurable and is pretty much definitely going to kill her relatively soon, say within a few months to a year. It's kind of important that she genuinely thinks she's very near the end, since I need her to be in a desperate "nothing left to lose" mindset where she's willing to make reckless decisions. -The illness keeps her from being very active, but she can still move around with effort, speak to people and think clearly most of the time. -She is not hospitalized, but may have a private nurse or something like that since her family is fairly upper class. Essentially I need her moping around her parents house just waiting to die. (I'm not sure how realistic this part is.) -She keeps seeing a "ghost" that nobody else sees. If feasible, she may not be sure if it's real or a hallucination caused by the illness. However, that is not especially vital: I can make it work even if the illness wouldn't cause hallucinations and she believes the ghost to be totally real. Now, supposing I go with the cancer, I can look up general stuff like common symptoms easily enough. What I need input on if how believable my scenario is, what kind of treatment she'd be likely to get and how that might affect her situation, and other more situational issues I can't just look up on Wikipedia. Really, just assume I know nothing about this stuff. I'm also open to suggestions for alternative afflictions, if anyone can think of one that would work better for this.