What the hell? Are you going to a AA meating in a amish community or something? I have met several people in AA that are dual diagnosed. They take meds for a mental health issues, and would not be normal without them.
I think that you need to follow your doctors orders and take whatever he tells you in the amount that you should. If you have a back injury and your getting back spasms, your doctor will probably give you muscle relaxers for it, which is very mind altering. What then? Will your AA group and sponsor tell you that your not sober anymore, and that you should not take your prescription? What whould they really know about recovering from a back injury?
Dune