Foot drop

FHSD does not affect nerves per se as it is a condition which affects certain muscles. Through its interactions with your body it might be possible that those interactions affect a nerve, but it is equally possible that you have a condition that has done the same, perhaps an old injury.
But that is pure speculation. Your description suggests that this foot drop happened quite suddenly without any pre knowledge of change, if that is the case then your doctor may well be looking at other causes for your foot problem. My own FHSD has limited the moment in both feet, and in my toes too, as well as having peripheral neuropathy. It is something I accepted might happen and I just need to deal with it. On that basis I would strongly support catatude’s advice to think through any potential surgery very deeply, especially when considering that it may well provide good benefits for you without the need to have an anaesthetic. This latter is very important with those of us who have MD, and you wold need in depth discussions with an anaesthetist about it.