Vibration feelings in pelvis

TNG • Married. 3 yr old daughter, 3 month old son.
So I have had this weird rumbling/rolling feeling in the center of my pelvis for the last 48 hrs. At first it felt like I literally had a cell phone on vibrate inside my body. I AM NOT PREGNANT. I know this for sure. What is this? Even if I concieved since I last tested i wouldn't even have implanted yet. Has anyone ever expirienced this and know what it is. I have a lot of odd things going on with my body the last couple of months and am going to the dr next week to tlk about the possibility of PCOS