As long as the pain isn't so bad you just want to cry and more of an uncomfortable ache then I wouldn't worry to much. Is it near your belly button? Or ribs? Are you drinking enough water, being dehydrated makes false contractions worse and your far enough along where you can start having them. Sorry if tmi but it could be digestive issues, If so I suggest sunnyD it works wonders and its cheap. Your baby maybe going through a growth spurt, my belly is always sore when my little one goes through one.
baby could be moving around. but if it is unbearable give your OB a call.
As long as you are not bleeding and cramping at the same time you should be fine.