i used to get something like this triggered by similar thoughts all the time, except in a different spot. if i started feeling really hopeless, like a lot more than average, i would get this, like, emanation of pain that would course its way throughout my teeth. sometimes it would come from my stomach or torso as well, and sometimes it felt less like pain and more like a big emptiness or black hole was forming inside of me. mine wasn't sharp like yours is though. i would describe mine as sudden but still gradual, if that makes any sense at all. i don't really get it much anymore, i'm not sure what changed. i tried to research it around the time i was getting it. i can't remember how i went about that, but i do remember reading something along the lines of how it could be a physical manifestation of really deep mental/emotional pain. like your brain sees that you're in deep pain over something, but there's no physical reason behind it, so it makes one up for you and says "uhh idk what's happening i'm just gonna make this thing hurt" and just chooses somewhere in/on your body. my mouth isn't in the best shape to begin with so i suppose my brain had no problem using it as a scapegoat. idk if you find your feeling painful, but maybe this explanation could still apply. but i don't actually know anything so no promises this is right.