That sux Amy. Really sux.

Is there anyone else you can speak to? A mentor? A senior manager? Get them on your side and explain (calmly) what's happened, and suggest that as the AGM is not very far away, it is best that you continue with the work for this year. Changing your JD around is pretty annoying, and they should go through some internal process to get it approved. Maybe talk to your union?

Are you on AWA? If you're not, then its harder for them to change your job. And if they use the excuse that your illness made it best to change the JD, that's discrimination right there - and you have grounds to pursue.

good luck