38 weeks and diarrhea

I'm almost 38 weeks and I started having horrible cramps after my cervix checked ( 2 cm), 4 hours later I started having horrible diarrhea. It's been 20 hrs now and it's not getting better, I can drink or eat. I'm afraid of becoming dehydrated now. A few people said this could be a sign of labor. I don't jus what to think. My back is so sore/cramps.