I can't tell you what is wrong with you. I do understand what you're describing. It sucks and it's hard. I've had the same problem for well over three years now. Nothing I've tried has rid me of it. I have learned to live with it, though. I've come up with different strategies and they work for a while, then I have to come up with some more. Over time, I've lost the ability to even be happy with others around me. Having people around has helped, though.

My advice, find a strategy to stay alive whilst you're alone. Don't wake up in the morning and say, "I'm going to stay alive today." Wake up and admit you don't know what will happen. Live day by day, hour by hour and so on. Get down to the seconds if it works for you. You don't have to take my advice. What works for me may not work for you. I didn't want to listen when I was told the same thing, I had to learn it through experience.

PC is a good place to resort to when you're alone. It has helped me. I hope it can for you, too.