Hi Womble,
no AA sponsor should "play Doctor", parting ways with this person was a smart move. AA is about abstinence from alcohol, the fact that you are using prescription medication to reduce anxiety or any other health issues is non relevant. Every substance we take into our body could be described as having "mind altering qualities" be it nicotine, caffeine, chocolate or even the oxygen in the air we breathe in to survive! Please take your doctors advice about medication, try a different AA group and hopefully a new sponsor and just concentrate on your sobriety at the moment, reduction of other medication may then become possible without a return to alcoholism.