well I do know from other that have said thier t.n started after dental work and too it is not that uncommon for one to have the T.N nerve damaged in some way by an infection like a sinus infection ..or abscessed tooth. the infection travels to that nerve.
IMHO I would skip seeing any more dentists and oral pros and fight to get referred to a neuro Doc. a.s.a.p. they will be able to help you more then anyone in finding out if this is nerve damage and if it is some type of Neuralgia thats taken your face mouth and you hostage.
I wonder if cold or hot compress may help you a teeny tiny bit easy the pain?
no one that you have seen has given you anything for the swollen tongue and your mouth issues??
I hate to hear how much pain your dealing with.
if it gets to bad the Hosp should be able to try a nerve block to help you get some relief.
Your not alone even tho your suffering by yourself ... we are here and know ..we know and care. keep posting okay... we will help you figure this out.

PEACE
BMW