This is a pretty long thread already so I hope no one minds me interjecting, but I am so grateful to have found this forum. My details are different but the story is the same as so many others: sudden, unexplained localized twitch, Dr. Google, concerned primary care doc, cleared by neurologist, huge feeling of relief, twitching doesn't go away, doubts creep in, questions and what if's, nagged by stories of "exceptions to the rule" on the internet, etc., etc., etc.
And like niknakx, was at one point sure that this was it, trying to learn to accept death and figure out how to tell my family. Such a dark time.
I got out of that pit as the time went on and with more reassurance from my neuro, who needless to say is a pretty smart dude.
Still react to twitches with anxiety though. Fears that somehow it was ALS making itself known that it was coming, then somehow evading the neuro's examination, and waiting in the dark to strike when I believe I'm safe. It is not an easy way to live.
Again, grateful to find others going through and those who have gotten to the other side.