Im 39 weeks and 5 days pregnant, i passed some of my mucus plug last week and today i woke up with lower back and stomach pain.

Possibly Labor: Congratulations! And call your OB. You are likely in early labor. How fast you go depends on your body and whether or not you've had previous children. Good luck!

Pain?: When you say stomach pain, are you talking about labor pains? Is your baby still moving a lot? If you have any concerns at all, I recommend you call your doctor or go to labor and delivery to be checked. I wish you the very best!