Her PMS makes me crazy.

My girlfriend is acting weird for almost 3 weeks now. I understand that most women (if not all) undergo a severe pain throughout their menstruation and that they are beast-like during those days. However, my girlfriend's PMS isn't seem ordinary. We argue from time to time. Every time I talk when she asks for my point of view with something, she gets angry. On the contrary, she will curse me to death if I stay silent. She makes rants when I make a phone call. Isn't that scary? One time, I went to their house to pay a visit. I brought her food to make her happy just like the way she used to before. To my surprise, she got mad when she saw me. Those made me think something wrong is going on. Is that even normal for girls to have PMS attack for almost 3 weeks or is she doing something behind my back?