I thought that was normal after sitting in one place (or lying down) for a long time

The first time I had a migraine from allergies and constant weather changes I layed down for like 17 hours until it went away.
Genetics suck.
I really don't know if its normal, because only happens if I sleep a certain way, or lay my head on something really firm.

That happens to me.

Also I had a weird dream last night but I forget what happened. I remember it was odd though.

It happens to me everytime I sit or lay down and get up really fast. Like nooooooooow... Aw my head.

I can think back to a nightmare I had in preschool. It scared me that much.
I was in my basement and I go up 2 flights of stairs, and my house is infested by spiders and I run for my door, which is as far as I remember.
Edit: When I saw Duh's name at the bottom, I remembered watching like 3 Care Bear movies in a row somewhere.

I had a nightmare which I woke up and there was one of those Japanese horror movies girls looking at me. She was right on my room's door, and I got up and (somehow) managed to get past her, and I went to the living room and suddenly she took out my legs and I started to bleed and then I started to call my mom and she was watching television and acting like if I wasn't there. I woke up and she was watching television the same way she was in my dream

I usually have these reoccurring dreams of being chased in a forest that's full of hanged women, i never dream of anything less than nightmares when i do dream.

This is called orthostatic hypotention. It's a non-serious, temporary medical condition in which your body doesn't keep up blood pressure high enough while you're relaxed, and so when you stand up quickly the blood drains from your upper body into your lower body. The visual side effects and dizziness is simply the effect of your brain being starved of blood momentarily.

It's nothing to be worried about, but if you have episodes of dizziness that last longer than half a minute or so, you might want to consider getting in better shape.

Okay. I'm gonna sleep now and that nightmare Ryan spoke about really made me scared. After I watched all those Marble Hornets videos about Slender Man, I got some paranoia about him, I need 1 hour to fall asleep after I lay down on my bed and turn off the lights. Even with my brother sleeping on the bed that is next to me. When he isn't sleeping, he is still awake, sometimes I just turn on the lights, pray a little, go get a cup of water and then go back and see if I can sleep.

By better shape, do you mean less fat? Because I have virtually no meat on my bones. I need to get fatter.

I think he means you need to make some exercises. Like me! When my fat-dad told me I have more chances of having a heart attack than him, I started to make some exercises every day that take 30 minutes of my life, but add 3 hours to it
It took me 5 minutes to make that joke

Yeah, shape as in heart health. Having a more muscular heart (from exercising it) tends to keep blood pressure more stable, reduce upswings and downswings in pressure.

EDIT: Again though, it's not a harmful condition. It's like getting nosebleeds. Annoying but nothing to worry about.

unless it's a super-high pressure nose bleed, like cutting metal type pressure, in that case you will exhaust your body of blood in an instant.

"The human body can be drained of blood in 8.6 seconds given adequate vacuuming systems." — River Tam

If I run the flat of my nail along my skin, I can draw on myself in vivid red lines that last ~20 minutes, and every time I have a blood test I end up temporarily blind.