Pain in lower abdomen! Should I be worried???

Today I started feeling a pain in my lower abdomen. It's right around the area where I would feel period cramps, so lower uterus. But it's more of a dull, muscle soreness type of pain (not sharp like cramps). The feeling stretches across my whole lower abdomen. I was pretty active all day so I'm lying down now and drinking water. Has anyone else experienced this? Is it round ligament pain or Braxton hicks? Or I hope not early labor...