I have had this and some times it scared the crap out of me. I read this book called the "Power of Now" and I don't have this happen as often. When it does happen I recall what the book taught me and try to be "present" and the thoughts/feelings subside immediately. If they come back I just keep repeating what the book taught me and finally it leaves for the day.

It rarely comes back anymore because I've learned to catch it as soon as it starts, and then look at it as if I'm separate from it. I can't explain how it works, but the book does a real good job.

If your into reading maybe this book could help you too.

Peace
Tammy