I Was Diagnosed As Having A Split Personality. The Best

I was diagnosed as having a split personality. The best I can tell is that it first began in early school years. I can remember very little from fourth grade and none of fifth grade. I remember suddenly aware of things around me as I looked around and realized that nothing about my classroom, classmates, teacher, or what I was surprised to be learning.
Over the years I have experienced periods of "being gone". My daughter says she is aware of this due to personality changes. Could this truly be a second soul living in my body?