DAMN, I was having random electrical shocks all over my body, but never in my mouth. Mine was caused by a ruptured disc(C5-C6) in my neck. I had spinal fusion surgery to fix it, but they came back a couple of years later, although not as severe.
I ended up having a second surgery(C6-T1) and it's now a rare occurrence. Did they do an MRI of your neck?