Lower back pain, pelvic cramps

So I'm 34 weeks this week, and I've had cramping every day this week. Today it is especially bad. They feel like menstrual cramps in my lower abdomen and pelvic area. I've also been having cramping in my back and up my side, causing some pretty awful back pain. These cramps are constant when I do have them. Usually worse at night and mornings. I have an appointment with my OB on Tuesday next week. I plan to talk to him about it then but I wonder if I should be worried about it more? Is anyone else having these too?