Having a horrible thought that won't go away

I have locked myself in my room and I can't leave. Tonight at dinner I started this obsession that was along the lines of "what if my mom tries to poison me?" And now I can't even sit in the same room as my family. Part of me feels like it's true and she did, because she was kind enough to buy my food separate from everyone else's. Part of me is breaking down for being so crazy, this is borderline schizophrenia thinking that someone like my mom is out to get me. I'm scared because I read that sometimes if you are poisoned you don't even know and it could take days to kill you. I don't want to die. After dinner I was asking my mom to do something she has been supposed to do for two weeks and she just stared at me smiling. I feel so guilty for feeling this way about my family but I don't know what else to do at this point. I need some help to know this is an obsession, there's no physical proof she is trying to kill me and I should trust my mom but I don't which makes this all worse.

Seems to me I used to worry my parents had been 'replaced'... as a small child. I've had obsessions and anxieties from a very young age.

I suggest you tell your family you urgently need help. My father needed to be dragged to an Emergency Psychiatric center because of his unshakeable paranoia and delusions and he's gotten better. Seek out help my friend.

Interesting. When I was about six I had a very similar fear to Snaga, where I obsessed that I might stumble into an alternate reality where everyone and everything looked the same ... but was somehow empty of reality or meaning.

Regarding OP, what you're describing could be a variation on health anxiety or harm OCD, or it could be something more along the lines of paranoia. If I was guessing I would say the former, since you seem very self-aware and have feelings of guilt about your thoughts. Either way you should treat this seriously and seek out a therapist. Because the symptoms you're describing sound a little ambiguous, I would advise trying to find someone who's got experience in both OCD and paranoid disorders and telling them what's going on in careful detail to help ensure a correct diagnosis.