Sydney,
I don't know if this will help you or not but your post got me curious.
I'm sure someone will be able to give you more info, in the meantime I thought what I had found was interesting as I had never heard of this drug before.

I found that Namenda is in a family of meds called NMBA receptor antagonists and that these meds are used often for neuropathic pain.

I know that isn't much info but I find it interesting the off label uses they have for so many meds.
The first time I filled a script for neurontin many years ago it flipped me out and I though the Dr wrote the wrong script when it said it was for seizures..

I hope you are able to find the answers your looking for and more then that I hope you get the relief you need.
Like you I have tried many meds not nearly what you have though.
Good luck,
Linda