Where Do Dreams Come From...?

.... I'm just wondering about that this morning as I prepare to study. 

I'm distracted every time the cut on my finger catches my eye.

The cut is from the back of a knife. (I only thought that was impossible.)

It doesn't hurt that bad and it's fine, but I had a dream about it last night... 

A rather disturbing dream.

It was one of those that I'll think about all day.

I'll tell you about it...

I was looking at the cut on my finger and I suddenly realized that something was in my finger like a splinter or a small piece of glass. So, I started fidgeting with it. All of the sudden, the cut popped open because there was something bigger in it than just a splinter. I freaked out, but I wanted this huge green thing out of my hand, so I squeezed around and maneuvered it out. It didn't hurt one bit. When I pulled it out, it kept coming and kept coming.

It was disgusting. I'm grossed out to think about it. 

It was about as thick as asparagus, but it was hard like a bone, and it was as long as my finger.

I thought that I had accidently pulled my bone out of my pointer finger.

The people around me were repulsed.

And I didn't know what to do except not move my finger and hold this bone-like thing, in case the doctors needed it to put back in my hand later.
I stood there, confused and scared, unable to do anything.

Then I woke up, and I was so happy that I was not holding a bone in my hand.

So the thing that is disturbing:

How in the world do these thoughts enter my mind?

Do I think them up myself?

If so, there might be something wrong with me.

I hope these thoughts go away.

I really need to study.