Back Labor?

I had tailbone and back pain so bad last night. I stood up after getting off of the bed and fell right back onto it. I tried to stand up again, slowly. Ended up on my hands and knees. Tried to get up and I had to give up, I couldn't do it. But I had to pee so I had to find a way downstairs, I held onto everything I could but it was harder to walk through this pain than it was to walk through contractions with my first baby, I'm thinking maybe it's back labor? Does anyone know what it could be? Anyone else experience this before? I'm 36w 4d and was just 1cm on Monday but he's head down and in position. I also feel pressure on my cervix.