Why do I feel this way? Am I the only one?

I get this... weird feeling sometimes. It feels like I'm disconnected from my body, and I feel like my brain isn't attached in the back of my head. While this happens, I feel really worried about little things, or even nothing at all to my knowledge. I get a headache and my heart races. I also tend to think about more violent things like gory thoughts and sometimes I self mutilate. Nothing big, just like pinching excessively and mild cutting, to the point where I'm barely drawing blood at all. Am I crazy, or am I not the only one?