signs of labour starting?

Shelbi • TTC #3 PCOS.
Hey ladies I'm currently 40 weeks + 3 had a sweep on Friday & so far nothing.. I was woken up this morning by terrible backache that hasn't eased of anymore.. I ended up down maternity assessment unit tonight due to having green mucus discharge but all is fine & was let home.. update is my back is killing me & having lower stomach pains.. could it be the start of my labour progressing? Any insight lovely ladies would be greatful! X