What kind of disorder causes drop foot, loss of balance, twitching, tremors, dizziness and can be completely cured by taking a benzodiazepine?

An anxiety disorder: Plus or minus conversion disorder can give you all the above symptoms--and I have seen several people with such presentations. You may want to treat with a good psychiatrist who can provide long-term treatment without resorting to benzodiazepines, though. There are significant problems with benzodiazepines, especially if one uses them long-term. Take care.