Hi,
I've had "burning mouth" since the onset of my PN almost six years ago. I just had a bout of it last week with my worst flare up in a couple of years. No one seems to know how to make it better, would love a lidocane mouth rinse myself. I burn in tandem with a flare up in my feet, the best pain reliever for my feet is cold water so I held cold water in my mouth too. Didn't completely take the pain away, but it helps for a bit. It hurts more after eating so I brush my teeth right away. Good luck with this, it really hurts and its hard to distract yourself from mouth pain.