Back pain

Becca
Okay, opinions. I am 40 + 4 weeks pregnant and haven't had hardly any symptoms of labor up until today. All day I have been having this excruciating lower back pain ever 10-15 mins. It doesn't seem to go away no matter what position/place I get in. I took a hot bath tonight to see if that would help, but no luck. I'm trying to decide whether I should try calling my on-call Doctor/L&D or if I should just hold out for contractions or some other sign. I hate the idea of being a pregnant woman that "calls Wolf" when not really in labor. 
Thanks!