Is it normal that i get a feeling in my back when someone behind me?

I had that when I took a shower in prison.

I get this all the time, but most of the time ignore it or don't even notice it happening. However, I can feel it in the upper or middle part of my back. Most of the time, it's the upper part.

Sometimes when it's dark or I'm alone (or both), the feeling increases to the point where I feel genuinely scared. I also hate it when people walk up the stairs behind me without me knowing, because then I run like hell.

Especially with my brother, because he just literally runs right up the stairs faster than anyone and it makes a loud noise that I'm sure the neighbours can hear.

Yeah you seem to have a environmental awareness warning system in your back, may be useful if your like a ninja or something

It's a sign of latent clairvoyant abilities. It's nothing to fear and you've no reason to worry. It sounds like your inadvertantly "fighting" against it. You must stop seeing it as an abnormality and stop seeing yourself as a freak. As you've been conscious of it since childhood, this should be fairly easy. Simply close your eyes and imagine this feeling spreading through the entirety of your body, let it become you, to the point where you no longer see it as an oddity, but normalcy in you. The only real issue you may have with this is if you're already subconsciously aware of your chakras and one or more have become blocked, which is very rarely issue if you're under the age of twenty. If you're older and that method does not work, I recommend looking up materials on "chakra cleansing" it's a lot to explain in a comment. At any rate, the only reason you feel "bonkers" is that those you mention this to dismiss it or tell you that you are such. You're not. You're an exceptional and gifted individual. There are ways you can learn to control it, books are your best bet, internet sites tend to be full of rubbish more often than not. I recommend the book "Teen Psychic" by Julia Tallard Johnson. You're true age is unimportant, as this is very effective for anyone of any age at your level. And, no.. This will not make you a psychic or superhuman. It only helps you to understand what you are experiencing, how to cope with and control it and how to further your understanding and grasp, if you wish. I hope this helps.

I used to get this and sometimes still do. I thought I was a weirdo.