I wanted to know if my girl freind was Pmsing Please Help ?

So this been happening for 3 days now and I noticed that she was acting a little strange I asked her are you okay whats wrong she says nothing Im okay. I try my best to help her clean and do my best to support her. Sometimes If I say I don't think you should of got that dog or are you going to clean your room and I feel like shes a bit overreacting. Even if I tell her shes over reacting she just gets upset with me. When she gets upset at me I tell her lets talk it out she says there's I cant and starts blaming me Im tried of you doing this and that I cant really reason with her. I don't know is it my fault or shes just annoyed of me or i'm doing something wrong .her moms in the hospital too but I ask her about it and she says its okay I'm not letting it get to me I think its the best place for her. I said okay. I try to ask her every day how she feels maybe shes just annoyed lol because I see her almost every day. Usually shes always sweet lol but at a certain day of the month she starts reacting on me lol.