How concerned would you be..?

Ma
I'm 34 weeks, and yesterday out of no where I started getting a pain in my lower back. I tried all sorts of positions and even had my husband massage the area and nothing makes it stop. I tried Tylenol and it did absolutely nothing. 
Currently it's mostly focused on the right side and it hurts to move or walk. 
I don't think I'm contracting.. And if I am I'm unaware. I have an appointment on Thursday and I think I'm just gonna wait it out till then unless it gets worse.
Would you be concerned that it might be a sign of preterm labor or just normal pregnancy pain?