--increased heat and body temperature exacerbates neurological symptoms--heat is the enemy of smooth nerve signal transmission. (Nerves seem to work better in a moderately cool to warm environment.)

The multiple sclerosis people talk about this all the time--increase in symptoms with heat is well documented in MS, enough so that there's a big industry selling cooling vests and ice packs to that patient population. It's also an issue for people with peripheral nerve damage--although, for people whose damage involves the small, unmyelinated fibers that subsume the sensations of pain and temperature, any temperature extremes seem difficult--and if the damage is extensive, it may be hard for them to tell what the temperature actually is.

As far as the meds you've been taking go, I'm sorry you haven't had more relief. For many, finding a med regimen that works is very trial and error, with multiple meds being involved for maximum effect--I know many people who take meds from both the anti-depressant (i.e., Elavil) and anti-epileptic realms (i.e., Neurontin, Lyrica) and do well with the synergistic effect. some even add in something from the opioid area to get maximum relief. And don't forget supplementation--such things as B1 Benfotiamine and Lipoic Acid have been used for symptom relief for neuropathy for a long time, even before a lot of the current drugs were formulated. They tend to have lower side-effect profiles, too.