Hans, welcome to the group!
I read your story with great interest....your English is superb, by the way!
I have had every one of your symptoms and more besides. And after long tedious periods of diagnostic limbo and misdirection, my doctors and I believe we have finally figured things out. It's a complicated picture involving both infectious diseases and associated autoimmune reactions in me which seem to have been triggered by various types of bacteria and viruses.
My battle with serious illness began in 2004. It was such a mystery at the beginning. The story is a long one, I probably shouldn't post all of it here. If you are interested in all the details, here is a link to one of my blogs where I have written many of them down: http://lymetwistontherocks.blogspot.com/2010/10/warning-warning.html
I was diagnosed at a early age with two autoimmune diseases: Hashimoto's thyroiditis and psoriasis. But my psoriasis has always been fairly mild, and although my Hashimoto's has NOT, once I was diagnosed and on the proper thyroid medication, things seemed to be going well for me, health-wise.
After I became very ill, with many visual, muscular, joint, gastric and neurological symptoms as you have had, plus serious brain fog and memory loss, I saw a large number of doctors (rheumatologists, neurologists, hepatologists, gastroenterologists, internists, etc), and they diagnosed me with:
At this point I had 6 autoimmune diseases and fibromyalgia, which may or may not be an autoimmune disease. I found myself on high doses of prednisone and Imuran to suppress my immune system and prevent further damage to my organs, especially my liver. A liver biopsy was done, it showed Stage 2 liver damage.
Blood testing revealed that I have the HLA DQ8 genetic marker for celiac disease, although my biopsy was negative like yours. My neurologist agreed at that time that my ataxia was likely due to my gluten issues. I promptly went gluten free, and ended up with my entire family on a gluten free diet.
One of my friends in an online celiac forum was shocked at the number of autoimmune diseases I had been diagnosed with over a period of approximately one year, and suggested I should be tested for Lyme disease. She explained that Lyme disease can both mimic AND trigger various autoimmune diseases, including celiac disease, lupus, RA, ALS, MS, etc. I laughed at the idea at first, because it seemed so unlikely! I wasn't a camper or hiker, just wasn't "out-doorsy".
But I had several symptoms that were still unexplained, including severe lower back pain, so I finally agreed to get tested for Lyme and some of the "coinfections". NOTE: the blood testing for Lyme disease is currently VERY inaccurate and a negative test does NOT mean that you don't have Lyme, although a positive test means that you almost certainly do!
So I'm sure you've already guessed that I tested positive for Lyme, plus 3 other tick-borne diseases: Babesiosis, Ehrlichiosis, and Bartonella. The first two, combined with Lyme, may explain what happened to my liver in 2004. Babesiosis also causes night sweats and "air hunger", among many other symptoms, and both Lyme and Bartonella can actually re-program your immune system and trigger autoimmune diseases. Plus, Lyme is notorious for causing unexplained back, neck and joint pain.
I am not a doctor, so of course I cannot say whether or not you have Lyme or any other illness or condition; but I encourage you to read up on the subject, please! I also encourage you to try to find a "Lyme-Literate" doctor to check you over for Lyme. Lyme is a big problem in Europe as well as in the US, and the testing and treatment protocols are very out of date (most countries try to be in step with the CDC and the IDSA here in the US, which is not a good thing). Here is a link to an online group that may be able to help you find the right doctor in your country if you decide that you want to see a Lyme doctor: http://www.lymeneteurope.org/forum/
The bottom line is that I WAS eventually diagnosed with celiac disease, plus many other things, several of which can cause my ataxia and my vertigo and all of my other symptoms. But it's really quite complicated: I have 6 autoimmune diseases, at least 4 tick-borne illnesses, plus fibromyalgia, and very high titers of antibodies against the Epstein-Barr and Cytomegalo viruses. My doctors have me on two conflicting treatment protocols: long-term antibiotics and anti-malarial drugs (Babesiosis is related to malaria) to kill Lyme, etc. plus immunosuppressants to protect my organs from my own immune system. Hence it is very difficult for my weakened immune system to fight against the infections, I've been on antibiotics for nearly 3 years now. I have seen some improvement in my memory and concentration, but not as much as I would like.
Note: you might want to use Google to research the "politics of Lyme disease" so that you understand how difficult it can be to get a proper diagnosis and treatment in the US. I've heard that it can be just as bad in Europe, depending on where you are... not sure about the Netherlands.
Here are a few helpful links to get you started on the subject of Lyme and its symptoms, diagnosis, treatment, and controversies:
Take care, and good luck in your quest for a comprehensive diagnosis!