Nightmare

I couldn't sleep last night. I woke up at 3:30 after having a scary dream. 

Which is very rare. I never remember my dreams NOR do I rarely ever have nightmares.

I think the last time I had one was when I was little. 

All I can remember is a huge black cloud and a big yellow lightning bolt chasing me everywhere, through a really dark old house and it's creepy back yard. 

What does this mean!?