37wks terrible cramping??

37wks almost 2cm dilated. 3rd baby but other 2 were induced so I've never felt what real, non medically induced labor feels like. doc said i'm having contractions so I must be mistaking them for something else. She said I could go into labor any day now. A new or at least worsening symptom I've been having last 2 days is persistent menstrual type cramping. It started out very mild but is now becoming quite uncomfortable and accompanied

by upset stomach. Anyone else experience and is it an indication that labor is about to start??