You cannot use dextromethorphan if you are using Cymbalta or Elavil. (or any other antidepressant that affects Serotonin).

Dextromethorphan is the isomer of levomethorphan which is a CII narcotic-opiate.
http://en.wikipedia.org/wiki/Levomethorphan

It has been used in some pain states, but has mixed effects. Not everyone finds it useful.

Elavil is the only antidepressant that has recently been shown to have effects on nerve growth factors.

5 days of Cymbalta is not long enough for much effect. The effects of Cymbalta are central in the brain, not the periphery.
Cymbalta and other mixed antidepressants affect perception of pain in the brain.

My cats are both black. It is difficult to get photos of black cats in low light, which is needed for the lights to show up when lit.
I cropped the photo as artfully as I could, but it is not sterling, I agree. I liked Weezie's paw on the yellow bulb...that is why I chose that photo.

The glial cells do not go away. They are the framework of your nervous system. It used to be thought that was all they did, but now we know much more about them. I have not seen papers discussing loss of receptors after opiod tolerance issues. I assume they do not go away, or if they do it would be a slow attrition.

I think at this point you need to address what gave you the PN in the first place. If it is triggered by some environmental thing, you may remove it and improve. I see from your first post you use anti-retroviral drugs? There are specific treatments for PN for patients who do so. One is acetyl carnitine. Some of the websites for patients using these drugs have extensive recommendations for the PN that may develop.
Have you been to a good podiatrist? Had an thorough exam for mechanical issues in the feet?