Is It Constipation or Early Labor? What Should I Do?

Okay guys, I need help with somethin and this is somethin i dont talk about with other people, its not a big deal to most but my family just doesnt talk about it. I cant go to the bathroom..like poop. Ive been up and down since about 2:30 this mornin with some of the worst pain Ive ever felt and I dont know what to do. Its killing my back and my lower abdomen right where like I thought my bladder was and where the baby's head is. But i dont know how to help it. This is the first time that ive ever not been able to just deal with it until it fixed itself. But i cant do this all day. But there have been a few times that I wondered if it was early labor. I dont know what to do. It goes away and comes back every so often and it hurts bad enough I want to cry and have cried at some points today. Im afraid if I call the doctor they will think Im stupid since I cant tell the difference.