Twitcher78--
Maybe I misunderstood your post, but I would think twitching AFTER exerting a muscle is not the same as twitching DURING exertion of that muscle. I was able to stop a real thumper in my bicep by flexing it and using the arm; once I'd stop, the thumper started back up. Drove me crazy, but it was gone by the next morning. In fact, many people here have noted that they sometimes induce twitching by stretching, flexing or otherwise using a muscle, plus twitching in a muscle following exercise is normal for many people, even those without BFS. So, if you're getting twitches after exerting a muscle, I think that is "normal" for BFS and nothing to worry about.
Mark