Labor?!

Okay so I had a doctors appt today. (37w5d) turns out I am 1 cm dilated and 70-80% effaced. Well I've also been in pain all day. A few hours later I had the normal light brown spotting from getting my cervix checked. There was a lot. And when I got up from the toilet, my mucous plug was in the toilet! And now, for the last 3 hours, I've had really intense lower back pains. Every 3-5 minutes apart. Isn't labor in the front too or what is even going on!?