My tongue has a mind of its own

Returning to the dentist today for my cavity work, I discovered that my tongue does not behave the way I expect it to. I moves on its own and even when I tell it to go somewhere (for example, to one side of the mouth) it may or may not. The weirdest part about it is that I have NO idea where my tongue is at any given moment. Sure, I can tell it's in the center of my mouth and touching the inside of all my teeth right now, but if my mouth was wide open (as it was on the dentist's chair) and my tongue was NOT supposed to touch anything, then when I tell the tongue to go to the right (away from the drills and instruments), I believe that it goes to the right. However, it also lifts up on the left side and into the way of the tools. I had no idea that it was doing this. Apparently I have defective proprioception (the sense of where your body parts are relative to the other body parts) when it comes to my tongue. It wasn't until I was handed a mirror that I could see what my tongue was doing and then adjust. Only then would my tongue listen to me.