I can't answer about the thyroid and nerve function, but have your vitamin B12 checked. I went through all those tests too, to find that I have pernicious anemia.
Low b12 can cause the tingling, numbness, etc that you describe. I'm on shots every 2 weeks to keep my levels up. The symptoms are much less, but I'd had untreated pernicious anemia for so long that the doctor says I have permanent nerve damage.