I've had head drop for 6 wks with no relief in sight after having 200 units of Botox injections for migraines. When will it end?

The injecting neurologist told me that there's nothing that can be done and that it will wear off. I have severe neck pain and strain and the muscles in my face feel like they are getting pulled as though those muscles are trying to compensate for the muscles in back of my neck. I'm in horrible pain...in agony. I'm wearing a neck brace to help hold up my head so I can go to work. When will this end? Is there any chance this is permanent? This is devastating.