Hey Nordicgirl,
Sorry to here so much is going on. I have alot of similar problems and it started with back burning years ago, then constipation, then headaches, weakness, walking problems, heat and exercise intolerance, vision problems and short term memory problems. I have had surguries on the spine, lots of tests (celiac, MS, lupus, cadasil, lyme, thyroid, vit Bs, EMGs, MRIs, etc). I was just tested for MG and waiting on results, but all the syptoms don't match. My one neuro thinks I have a metabolic mitochondrial disease. That is very hard to determine because it takes one of the few specialist that have all of background to do it. I will try to keep in touch.
Did you have headaches with your problems??