I don't know that these were the first signs that I experienced, but they were certainly present early on (and, sadly, they never left). I don't think your experience is that atypical - though, even if it were a less common experience, I hope that you would still be willing to share. There is such a multitude of different way that ME/CFS can manifest, it is almost certain that whatever your experience and however uncommon it may seem, there is going to be someone else out there who has gone through something similar - and who quite likely is dealing with some of the same uncertainty.The first symptom was a burning sensation in both wrists, which I treated as tendonitis. After one week it took over both of my achilles tendons, finally the pain was spreading throughout my whole body, including tons of other symptoms such as dry and burning eyes, light sensitivity, severe fatigue, insomnia etc.
Also: welcome to the forum, @Ranma! It's probably been about 40 years (oh my God...) since I read Ranma 1/2 during its initial run, but your avatar brings back memories of better times.