Back pain active labor?

Cassidy • Mama to Kinsley ❤️ Expecting our second precious babe 🙏🏻

Alright 35 weeks 3 days with my first..I’m having this pain in my lower middle of my back - is this babygirls positioning or a sign of active labor? I see the doctor Friday for my strep b test etc. Not sure if it’s something I should be alarmed about?