Shooting Vaginal Pain - 28 weeks

Alissa
Hey all, 
So, yesterday I decided it was a good idea to re-arrange my basement, I tried to be careful and not pick up anything heavy but I suddenly started experiencing a shooting pain in my vagina. I stopped and went to go lay down - felt better after a nap.
Today, I was walking up the stairs and got that same shooting, stabbing vaginal pain. Baby is moving but I'm debating if I should go get checked out as my next OB appt isn't until next week. 
Really worried :( am I starting to dilate? Did all that activity cause the baby to move down? Could I be in preterm labour? Anyone experience this before? 
Thanks in advance!