Doc. has really good advice. I only considered schizophrenia because of seeing things that are really there. Serious symptom of someone who is. However if that is the only symptom it is likely the doc. is correct. No way to tell until you speak with a doc. personally.
You find your school has a therapist you can speak with, but I do encourage oyu to speak to your parents first.
Best Regards
You are describing a very strong and intense guilt experience that is being played out graphically in your mind. You feel guilty about something but probably are not sure about what. As long as you don't know what it is, your mind is creating these scary images to make you think about it, and face it. In almost all cases, the underlying guilt is not at all important, but you don't know that until you see it for yourself. Ask your parents to help you get counseling...talking this through a few times with an experienced therapist may be all you need....and don't think about researching shizophrenia...start with the guilt.
I'm not sure. You sound really, really sad. I would think you have either experienced trauma or are experiencing some psychotic symptoms or are maybe even depressed. I don't know. You would need to see a doctor for a diagnosis.
I would strongly encourage you to talk to your parents and then a doctor. I would do this as soon as possible as this sounds like a lot for you, for anyone, to deal with.
Take care.
J