It started off as normal as these things can: as a child I had an imaginary friend. According to my mom I called him Leo, and when she asked what he was doing I would reply that he was standing and just watching. I have seen him ever since. Leo is an about 6 foot 4 shadow person. I started really noticing him again when I was a junior in high school. It just started off as seeing him in the corner of my eye but soon went to seeing him at the foot of my bed and in other places. Some select friends and family have reported seeing him around me too. Normally that's it. He observes and I've grown quite comfortable with the routine, however occasionally something (like a book) will go missing while I'm turned around and be missing for days and show up in completely random places (like in the back of a cupboard). Then events got more serious. I met my best friend Lauren. Now he doesn't seem to like her at all. Things will be thrown at her while I'm in the room (always her things) and she will experience loud banging on her wall at night. When she gets freaked out enough and calls me, as soon as I announce I'm coming over everything stops. When we moved to a Christian college these little crosses showed up random places that no one could have put them. I'm 20 so this has been going on for a long time.
I also hear voices of unknown sources quite often. Many people, even friends and family, don't believe me most of the time. Also, I often predict events that happen to me and have a very good gut feeling. Oftentimes large crowds are exhausting to me because I experience many emotions. When I dream I'm a almost never myself and experience a life through someone else's eyes and usually wake completely disoriented. I also sleep walk and sleep talk, pretty seriously in fact. My parents would have to put a special lock on the door because I was walking out of the house and coming back with huge bruises and no memory of what happened. I also have had some creepy moments while sleepwalking. For example, I hid under my mom's bed and waited for her to almost be asleep and crawled out and screamed boo. When she reacted I laughed a single "hah" and went straight back to bed. This terrified my mom.
All of this (except the top and sleepwalking and talking) is fairly recent and is slightly hard to cope with myself.
Reading your story, I can see the severity of the situation and I believe you could use some help. I have met similar experiences before, so I would be glad to lend you a hand. I have put my email on my profile, so if you are interested, feel free to email me anytime so we can both work on your situation.