Welcome to NeuroTalk:

Well, I think heating pads make PN symptoms worse. So I'd stop that for a while and see what happens. There is a type of neuropathy called RSD which is different from PN in that those patients crave heat. Most PNers, prefer cold treatments, but RSDers are intolerant to cold. We have an RSD (CRPS) forum here for you to check out as well if you need to.

A common side effect of Cymbalta is nausea. Also this drug stimulates the norepi nerves which can raise blood pressure and can cause headaches etc.

If it does nothing for you, I suggest you taper off Cymbalta, with your doctor's supervision and see what happens. Most PN symptom changes do take time, so be patient while you do this, as instant results typically do not occur.

It would be helpful to know more details about you and your symptoms.