My Nightmare hell.

I had a similar dream I found out someone was using a spell on me. But then I visualised a Buddhist temple (I'm Buddhist) and walked in and then all the animal walking and were nice to me (Buddha is friendly to everyone regardless or your religion except Christian as there is way to much death God kills more people than Satan!) and I believe the caster of the evil spell is now friendly and good!

your nightmares could be caused by a spell backfiring or a demon could be causing them. you may have even cast a spell accidentally. this means that your thoughts and emotions are causing your energy to use itself, which will make you more easily fatigued.
i cast an accidental spell once. i had nightmares for a while until i faced my fears and countered the with my will. you should try it.