If your tests other than nerve conduction have been normal, I would see a chiropractor. People think it is bones and muscles they deal with. The bones are levers and the muscles can pull them out of place and put pressure on the spinal cord causing pain and nerve conduction abnormalities. Even if the source is the brain rather than the spinal cord, there are ways to correct it in many cases. I would find a chiropractor who has a Diplomate in Neurology, Or look up Chiropractic Neurologists.
Insurance usually pays, and it doesn't sound like the things you are trying are helping. You need a diagnosis. I haven't heard of Lyme disease causing your symptoms.