Brief Answer:
Read below.

Detailed Answer:
I read your question carefully and I understand your concern.

I am assuming that by facial pain you mean trigeminal neuralgia....am I correct? If not please tell me, providing some more detail on the diagnosis and pain characteristics. Also you say you take "neurotoxin"...I am assuming it is a misspelling for Neurontin.

In terms of medication neurontin and amitriptyline are commonly used first line medication for that purpose, so I would say you are already under the best treatment (although you do not mention the dosages, perhaps they may be increased). Another possibility is Carbamazepine, the most widely used for that purpose but I assume your doctor has preferred neurontin because of fewer potential side effects.
Other medications may be tried like Lamotrigine, or Baclofen, but there is no guarantee they will work, they are not better, provide improvement only in a small portion of patients who have failed neurontin.

When medication doesn't work then some imaging guided procedures may be used. Common ones are glycerol injections, radiofrequency lesioning or ballon compression of the ganglion of Gasseri where the three main nerve branches join together. All these procedures deliberately injure the nerve so that it can generate no more painful stimuli for some months up to a few years. They are applied by inserting a needle or thin tube through the cheek inside the skull.

There is also radiosurgery which also uses radiation to damage the nerve where it enters the brain stem. Lastly in some cases where the pain is shown by imaging to be due to a blood vessel compressing the nerve neurosurgical decompression may be done.

I remain at your disposal for other questions

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