Can contractions feel like you need to poop?

Been feeling the sudden urge to poop about every half hour. But when I go to the toilet and push, nothing comes out. Then the feeling subsides, but everything (belly, behind, etc.) feels sore. Is this normal? Can that be early contractions? Baby was "VERY low" and felt like her head was "right there" at my appointment this past Thursday, but I wasn't dilated yet.