is this labor?

I've been having a constant tight feeling in my stomach. I know contractions are supposed to be intermittent, but I can't time this because the feeling isn't going away at all. It's been going on for a couple hours. I've gone to the bathroom, walked around, tried relaxing in different positions and the feeling won't go away. On top of that all, this is making me very nauseous. I'm 38+5 should I call the hospital?