I am happy to read this update that it appears you have a benign condition. I have a similar history of marathon running and extreme sports, as well as some similar symptoms. I have widespread fascics, including nonstop in the calves and frequent in the tongue. What are the nature of your tongue fascics? Mine are mostly just to the left of the tip. I also have sporadic cramps all over. Are you cramps isolated or widespread? How frequent are they? Are stories diverge with reflexes; mine are actually quite diminished. I had a recent EMG which was clean aside from fascics as well. I have had some exercise intolerance but I continue to run short distances and a slow pace. I have had symptoms for about 7 months. Were your symptoms preceded by illness, stress, medications or a combination? I have had some shoulder tightness when I hold my shoulder up, but this might be from wear and tear and years of exercise. I tend to conflate any physical problem I have now with this.
My symptoms are very similar to yours. They started in 2001, and continued for 2 years, and then they stabilized until last year by July, when they slowly starting appearing again. They're quite more severe now than they were 13 years ago. I never got any diagnosis back then, and I searching for the truth again. Best of luck to you. Do whatever you can do to get well. Eat healthy, sleep, try not to stress too much, and keep a log of your symptoms. The answer is somewhere