can this be a sign of labor?

Can an aching sick type of feeling in your stomach be a sign of labor? My stomach has been hurting like a poop kind of feeling for over 12 hours. I've also been really gassy since my stomach started hurting. This is my 3rd but I didn't ever get this way with my other 2. I'm 37 weeks 5 days. I'm at a 3 1/2 A's of yesterday and my doctor told me she doesn't think I'll make it to my appointment next week.