I was diagonised with BFS three months ago. I too suffer from a slight weakness in the left arm and thumb muscles but it seems to be only when I start using it after a spell and it does gets better with use i.e I regain better muscle strength and coordination after repetitive use.
I twitch after exercise sometimes but it has got better with magnesium supplements. I still get burning sensations on my arms and legs and eating chicken can make it worse so I no longer eat it.( Its a shame because I really liked it) . I am currently going to a vibrationalist who seems to be helping but reading what everyone else says here I will wait a few more months before I annouce any miracle cures.