I'm only going to address the back pain here: get him to a doctor, it may be VERY unrelated to the drinking or it could be referred liver pain. Might be good to just check it out.
My dad was an alcoholic and was having back pain, but it was unrelated to whether he drank or not. He actually had a spinal cord tumor that was pressing on the nerves in his back. He died last December, age 62, from kidney and lung infections brought on by the results of the tumor removal. He had an awful 2 years and managed to cut back his drinking but he was holding a cigarette until his dying days. It's amazing what addiction to any substance will do to you.
Now, my dentist, a 56 year old super healthy guy had back pain for 8 years and never really got it looked at. He was at the point last spring when he would have to lay down after working on each patient. Finally, after much prodding from his wife he went to a doctor and they found via ultrasound a HUGE liver tumor. He died within 6 weeks of this discovery. He was our family dentist for 16 years and we still miss him.
My point here is that back pain can be something very serious or nothing much at all. Have him get it checked out. Many times back pain is referred pain. Kind of how when my gallbladder acts up, I get shoulder pain.