I know you've mentioned in some of your posts that you have been on, and are weaning yourself off various medications.
I would suggest talking to your doctor about this if it concerns you. I've had insomnia for years, then started taking melatonin, and have been taking it for years. I know some will say this is unhealthy, but I'm doing so under medical supervision and for me, it's a choice of either take it or not sleep at all. And one of the most common side effects is vivid nightmares.
I often have dreams of people trying to kill me, and it will feel so real that it takes me several minutes to realize I'm in my own room when I wake up. I don't know if it's because I used to watch a lot of action movies in the past (but no longer do now) in which people were always getting killed.
But it doesn't seem to be something that's going to go away at anytime and I wish I could stop taking it, but nothing else I've tried has ever worked. "Natural" remedies are like the Sandman laughing in my face. So I do what I can to thank God that at least I CAN get some sleep and just deal with the side effects, repenting of things I find unnerving in my dreams when and if necessary.
I certainly don't have a medical background, but from the things you've mentioned, I wouldn't be surprised if your dreams might be a side effect of various medications or things you've taken, whether past or present. And it might be permanent.
I know the dreams (well, mine at least) can be be very disturbing, but I just try my best to take them to God, especially when I'm really shaken. I don't know what else we can do, aside from trying to live as healthily as possible and try to avoid meds except when they are absolutely necessary.
I pray things get better for you and keep us posted on how you're doing!