Blame it on PMS?

So...lately, my mood has been off the rector scale. Don't get me wrong, I have valid reasons to be upset. But lately I've noticed my reaction has gotten worse. It's become so bad I have lost respect for myself. It's become hard to face myself in the mirror because I feel like an idiot. Problem is I don't know why I'm feeling this way or how to control it. It usually happens before I start my period but, I know that can't be all. Has anyone else ever felt this way or am I alone?