I've had twitching muscles for, hm, 18 months now. I'm still here -- running, walking, carrying gigantic bags of stuff from Costco, etc. No Dread Diseases. Neuro cleared me as well.
It is extremely bizarre (and for those of us with HA, very upsetting) to see and feel muscles twitch. I too felt absolutely certain that something was horribly wrong. And I was right ... but what's horribly wrong with me is ANXIETY. For you, too, it is extremely unlikely to be anything other than ANXIETY.
By the way -- my sibling also has an anxiety disorder, though more of a social anxiety disorder. I was talking about my relentless finger twitches. Sibling was like, "Oh, yeah. Happens to me all the time. I think it's weird, but kind of cool." Said in the most indifferent tone possible! After I got over my shock that someone could receive a Sign of Certain Death with such nonchalance
, that response helped me to see that HA is distorting my thinking terribly on this topic.
If you haven't already, google and find another forum where people with BFS post. I read a bit last year, and it was illuminating.