I turn into a crazy bitch during PMS, help?

I am going through PMS right now and I am in a relationship. And I think I am destroying it. I get mad or upset over the stupidest things every 5 freakin minutes and then have to talk about it so we end up fighting and I never feel any better. I realize I am doing it and I hate myself for it, but I don’t know how to control myself! I take pride in being a level-headed, understanding girlfriend but then this happens and I become exactly what I hate. I’m trying hard as it is, but is there anything I can do to calm myself during these few weeks that I am a raving lunatic? Girls, do you have a similar problem, is it just me, is it the relationship maybe?