2+ moms, back pain = labor?

misskates999

So I already had a bad back before getting pregnant so I was expecting this pregnancy to make it even worse, but it actually hasn't!  For the first 36 weeks or so, no back pain at all! Now for the past few days my back has been KILLING me! It's mostly in the evening, but its worse than I've ever experienced and nothing seems to help.  A coworker of mine said that before going into labor with each of her 3 kids, she experienced the same thing. Does this sound right to anyone else? Should I be concerned about going into labor soon??