Back labor?

Caitlin
What does back labor feel like? I'm 39+1 FTM and I've been having very intense back pain, it never goes away but gets stronger then dulls down a little and kinda moves to my sides! I've been losing peices of my plug the last few days, and I was dilated to a 3 and 80% on Thursday! Any idea what might be going on?? TIA