and sure enough, I have an impacted wisdom tooth
!!! Undoubtedly, this was infected several months ago, causing infection
to get into my sinus cavities. It must have been really messing with the trigeminal nerve. Sounds like you didn't have the sinus pressure, so your problem may not at all be of a dental origin. But I thought I'd mention the very surprising root cause of my problem, in the off-chance yours might be similar. If not, I hope you find an answer... Best of luck!