I'm so sorry. I understand this particular situation is extremely difficult.
I was just wondering if it would be worth trying a compounded cream? I recognize that it is a bit of a long shot, but if other things are barely working, it might be worth the try.
I've gotten good results with a specially made topical cream for my atypical TN.
It's been almost four years and I'm finally in a decent place. The pain is still there, but I have much more control.
In my particular cream is: Lidocaine, Gabapentin and Capsaicin.
I rub it on the affected area about three times a day.
I originally used it five times a day.
I also take Baclofen orally.
My doctor and I had to try a LOT of medications to get to this.

Also, if you are not doing so already, please consider therapy. Having daily pain is very draining.
I have moments when I reflect on all my various health problems, the heavy duty pain of TN, etc and I wonder how in the world I have surmounted all that pain and the related difficulties.
I have had to go to therapy off and on. And, I've been fortunate to find caring and intelligent doctors....this is also of great importance and often takes multiple tries.

Wishing you strength and better days ahead.