Thank you for your reply. I hope that you are able to get off of it with success and that you have good news soon. Perhaps after 20 years your migraine pattern has changed. Finding a good "preventative" helps rebound. I've yet to find a preventative and simply cannot live with daily migraines anymore.
"God grant me the serenity to accept the things I cannot change, to change the things I can and the wisdom to know the difference. Amen."