Non-recurring nightmares

Hello, I´m new at the forums and this is my first post.

I have always had nightmares, but recently they have become more often, and what´s strange about them is that they are not recurring and seem completely unrelated one to another. I understand nightmare´s tend to repeat themselves, but it´s like i´m having a whole new nightmare almost every night. I remember some of the scariest ones, and they seem to having nothing to do with each other.

For example, one night I dreamed of having my limbs tore and eaten by some dog-like beasts, and the other night i dreamed i was following someone in a cave and got stuck in a very narrow tunnel, and in an other dream i was in a city that starts flooding with some dark mud, i go up a very tall building to escape but i end up narrowed in top of it, watching as the mud level rise and drown everyone.

I havent had any major loss or trauma recently, and I cant find a pattern on the dreams that help me to identify the cause, i think the only thing they have in common is the darkness, as it seems to be always night in those dreams.

Has anyone ever experienced this before? what do you think might cause such dreams?