Constant hard belly that feels like a contraction?

Rachel ❤💙 • Angel 6/20/15 👼💔 Rainbow born 7/10/16
My belly has been super hard like a contraction for six hours, every since hubby and I had sex and tried nipple stimulation. My due date was today. Obviously it's not like timeable contractions because my belly doesn't soften, but is it normal for it to stay hard this long? It's starting to get uncomfortable and a little painful.