Cramping Question

I started cramping in my lower abdomen a few hours ago. I honestly don't know what it is because I'm a first time mom. I don't know what contractions feel like but I'm thinking this isn't them since its constant and doesn't come and go. It's like mild to bad period cramps right in the middle of my lower abdomen/pelvic area. I'm 35 weeks. Anyone know what this means or why it's happening?