Back labor?

Has anyone had back labor before? I'm currently 32w3d, with my last two pregnancies I went full term and had to be induced, so I've never experienced going into labor naturally before. For the past 5 hours I've had intense lower back pain mostly on my left side, that kind of wraps to the left side of my belly. It doesn't feel like round ligament or sciatica, it's like an intense dull burning ache that won't let up, and the pain will get worse in waves. I've tried to time it out as if it were contractions, but it's hard because the pain doesn't really let up, it just gets more intense in waves.