From what I understand effexor is often prescribed for neuropathic pain (particularly trigeminal pain which is what you are probably experiencing). It is an anitdepressant.

Clonazepam is more likely to be prescribed for spasticity. I have taken it a few times when my leg is really bothering me with spasticity.

My neuro mention effexor as a possibility when I first started taking neurontin if neurontin does not work. Side effects do not sound pleasant. I have heard that mj helps more with the burning than anything else.