--that neuropathy just goes "up tot the knees" needs to go back to medical school; peripheral neuropathy can affect any nerve outside the brain or spinal cord, in any part of the body.

It is only the most typical presentation of diabetic and some other kinds of neuropathy that involves "length dependent die-back", meaning the nerves farthest from the center of the body are affected first, so that one gets toes, lower legs, and hand/fingers affected. Even with these types, the affected areas may "climb higher" with time if the progression is not arrested.

Part of the problem is that symptoms of compressive neuropathy, caused by actual physical, mechanical damage to nerves, or symptoms of problems with the spinal cord or nerve roots next to them, may exactly match the symptoms of neuropathy from more systemic physiological causes; this is why the search for cause if often long and expensive (and not always fruitful). But it would seem in your case they should be searching for evidence of nerve compression, perhaps through imaging, in addition to other testing.