Consistent Low Back Pain - early labor?

Melissa

I’m 38 weeks today and I had sciatica for most of my pregnancy until about 34 weeks. Since then, I’ve felt way better! About an hour ago, I started feeling very low back pain again all of the sudden. But it doesn’t get better when I sit, which was the case before. It’s not coming and going like contractions (2nd baby so I’ve been through normal labor before) but I’m wondering if this could still be the early stages of labor? Or back labor? Anyone experience this?