And having read the thread, I think the more likely problem is still somewhere in the spine. That's not to say that on can't be "co-morbid"--experiencing more than one problem at a time with similar symptoms (there are plenty of people who have both problems with peripheral nerve AND problems with the spinal cord or the nerve roots next to it, and because of the so-called "double crush phenomenon", may have symptoms that are more than the sum of these parts), but given your history, and the initial relief, I think the lower spine is the place to look first.

And yes, a good neurologist, or perhaps physiatrist (they often tend to be more integrative) , should do a complete NCV/EMG study of BOTH lower extremities, starting with the lower paraspinal muscles and doing the whole legs. The idea is to find out if there is a nerve signal abnormality and if so, where it originates from. This is likely to be a long, uncomfortable test, though, so be forewarned. Moreover, results often depend on the skill of the tester in placing electrodes, and on the temperature in the room (it's supposed to be cool in the room, as heat is the enemy of nerve conduction).

One thing I didn't see you mention--have they done a new MRI of your lower back and pelvic area? It's entirely possible that even if your L4 area is in good shape, there are problems at other levels that might contribute to these symptoms (the Spinal forum people here can certainly speak to this--surgery at one level often leads to additional loading at other levels, and often begets the need for more surgery). They should be looking at your hip and pelvic levels, too--compression at the hip and pelvis can also bring symptoms down the legs and even into the feet, depending which nerve pathways are involved--there is a lumbosacral plexus of nerves where a lot of these pathways merge, integrate, and then spread out again into the nerves of the leg and feet, and there can be compression there as well:

http://www.theodora.com/anatomy/the_...al_plexus.html

As you can see, it's often difficult to tease out problems of the spine from problems with the nerves a little farther, or a lot farther, along the pathways.