Never been this moody!

I'm suppose to start my period tomorrow, but these past couple days have been terrible. My boobs hurt, I just feel "sick", and I have been soooooo moody. I've never been this moody in my life, even my fiance noticed. I'm mean one second, laughing the next, crying the next, then laughing again. I mean its getting pretty ridiculous and I don't know how to stop! Could this just be my head? Period symptoms? Its stressing me out. :(