Help? Back, leg, and belly pain

I’m 37 weeks today and for the last hour I’ve been in straight up pain. It’s constant and not like contractions? It’s sharp and in my back, belly, and going down into my legs. It gets worse and then gets better but it’s constant pain. I called my OB office and I’m waiting for a nurse to call me back. I don’t think it’s contractions but not sure what it is or what I can do to stop this pain. No discharge, no cervix check recently, no sex, nothing. Any advice until I hear back from the nurse?