So nice to hear from you again but sorry your symptoms seem to be multiplying.
I think it's good that your neuro is doing additional testing. It's definitely my understanding we "oldie but goodies" have an increased likelihood of lesions from things other than MS so that it's important to rule everything else out. I never had an EEG though so can't comment on that.
Now, I do have an exaggerated startle reflex that sounds similar to some of the reactions you mentioned--although I don't drop when people, loud noises, etc. surprise me, I do jump. When it happens I tell people I have a hole in my startle reflex and to knock it off.
It is definitely good to laugh about it. Actually I really don't know if I have "hole" in my startle reflex, but I definitely know there's something wrong with it.
I hope your appointment goes well. I've no idea what the neuro may be looking for at this point since you've had lots of prior testing.
Take care and keep us posted. Hopefully some others will weigh in too.