Totally know the feeling!! I describe it as feeling like you are on the old school playground merry go rounds that has stopped spinning but you feel like it still is...
This is withdrawl! And it is the worst of the worst. My guess is 5 years at that dose, you dropped WAY to fast, three weeks is crazy fast! My doctor suggested to me to drop 5mg every couple of weeks and then on the third week try the new dose every other day. Example you are on 40mg.
Week 1 40mg on day and then 35mg and then back up to 40mg and then on Week 2 and 3 stay at 35mg
Week 4 35 mg one day and then 30mg
Takes some time but it beats being sick! I would suggest starting over! Go back up to your normal dose for a week. You will feel better almost immeaditatly!
It's a really scary feeling!!! But just know it just the withdrawl! Feel better!!