Back cramping for 6 days

Any mommies experienced low back cramping? I have the normal slight cramps in my lower abdomen but since I went to work and was on my feet 13 hours straight I've been having s lot of cramping in my low back. The best way to describe it is...it feels like someone is pulling outward on each side of my spine about 2 inches above my tailbone. I've been drinking plenty of water. I'm afraid I'm overdoing it. Any ideas or suggestions are greatly appreciated!