So it cannot develop otherwise?

Because I definitelly have some of these symptoms... memory lapses (I remember after my state exam on Uni, I went for a trip, by myself... I remember being on particular place and the next thing I remember is waking up in my bed... while I took pictures, I even have pictures I took of myself in the train... but i just don't remember it), out-of-body experience, not recognizing myself in the mirror... I even argue with myself... I would not call it alterego, because it is not a complete personality... it's just my lazy, whacky and unreasonable self, I guess.
And I cannot express these feelings in words...

...but to the point. I have not experience any trauma that would induce this.