I'm 26 weeks nearly 27 weeks pregnant

I've been having some mild lower back pain... But in the past couple of hours it's gotten fairly worse... The pain shoots from my lower back up to nearly my shoulders. It seems to be getting worse. With my first child I had similar pain but not until 34+ weeks... And during labor. This baby has been moving like crazy up until the past few days he's slowed down but still kicks hard and fairly often. Anyone know what this back pain is? A Braxton Hicks type of contraction, over using, under using muscles... ???