Annette Coscia hello and welcome to neuro talk.
I have anesthesia dolorosa and the symptoms you decribed sound very much like mine. the thing that i do not get is you said nothing showed on an mir.
i can share with you that i have a neuro stimulator that helps me and probly saved my life. I cant have an mri because of my stimulator but i know that before i had it implanted my xray scan thing did show my lower right trigeminal nerve snapped, dammaged . so maybe it would be a good idea to search anesthesia dolorsa and see if anything relates to your sister.
I am here if you want to talk or ask questions. it dose sound like some type of neuralgia thought even if it dose not show on any mri ...it dose not always show up and that is a fact. you are a great sister to be helping and searching on behalf of your sister.!!
let me know if i can be of help.
many blessing to you.
Peace BMW