Welcome to SR, I would suggest he see a doctor and be totally honest with the docotor about his drinking, and also whether or not he is taking his Xanax and other prescriptions as directed.
Xanax is called alcohol in a pill form by some folks.
It is VERY important that all of his doctors be aware that he is a recovering alcoholic, because as mentioned many meds can really mess with an alcoholic, especially if they are not being taken as prescribed.
BTW when it comes to withdrawals every one is different, another reason to see a doctor, this may or may not be withdrawals.