I am no expert, but I am wondering if there are some bad experiences stored in your brain that come out in your dreams. They do sound unusual to me.

You might talk to a therapist about the patterns that you observe in your dreams to see if there is a general theme.

Do you watch a lot of shows/movies/play games with those kinds of themes? That might be why you have so many memories of the scenarios of the end of the world, etc.