I Have Something to Say

I'm wondering what my problem could be. I'll explain. It's like I have two personalities. One is caring and compassionate, and the other is the complete opposite. I never know when the flip will occur, and I've yet to discover what triggers it, if anything. It could last for a few days or a few weeks. I'm not talking about mood swings or dipping into a depression. I actually feel like a different person, just with the same body. If anyone here experiences this, please let me know. I'd like to know more about it.