Next course of action for undiagnosed polyneuropathy

I have spent the last ten months working with medical teams to determine the cause of my sudden neuropathy symptoms. As a healthy, active man in my early forties, the very sudden (within a couple of weeks) onset of sensory symptoms in my hands and feet was very scary. It took me about four months to get into the care of my primary neurologist. Since that time, I have been through large batteries of tests, from multiple MRIs, blood, urine, cerebral spinal fluid, and skin/tissue tests. Besides high amounts of protein in my spinal fluid (which is non-specific), all of the tests have been negative. It has been comforting to know that these tests have ruled out some very alarming and life-threatening conditions, but frustrating because I continue to live with the symptoms that I do (though better controlled with medication) without being able to address a cause. But what now? My primary neurologist recently referred me to another at OHSU (Portland, Oregon) who I have seen. He reevaluated me, reviewed all my lab work, and basically shrugged his shoulders and let me know that the cause of many of these polyneuropathies is often unknown. He had no additional tests to recommend for me, and told me I didn't need to make a follow-up appointment unless my symptoms worsened. My primary neurologist just concluded my last test without a positive result. He has referred me to yet another neurologist up at the University of Washington (Seattle), and I have been warned I might be waiting several months to get in. I find myself wondering if I am being stupid by continuing to pursue root cause, or whether I should only be focused on managing my symptoms. I haven't been able to find any correlation between lifestyle, diet, and my symptoms, and these meds make me so foggy. I don't really know what else to do.