My guess on the nightmare is that you were experiencing hypnopompic hallucinations while in rem atonia. It is possible that is was an fa. You should be able to tell if you have awoken from a fa as well. On the one hand, you would wake out of a dream which seems pretty easily identifiable, and on the other hand you have an intense waking experience that seems more suited to a dream. In that hypnagogic/hypnopompic state, you can experience just about anything.

As a kid, I experience it without the rem atonia which was especially disturbing. That state is very much like a trance state; sort of like a halfway point between waking and dream reality. Its a very interesting experience for sure. There might be some symbolic meaning in the dream relating to waking life however, each person would have a different take on the dream. Another way to utilize a dream is to explore the emotional nature of the dream, and attempt to correlate the emotions with the metaphor being depicted. That usually produces a much clearer image than searching for specific meanings.