(Obviously, I did not mean yourself personally, when I said "you still get cancer," I meant a smoker can still get cancer even if they are smoking fewer ciggies. Alcohol is like that, for someone who has a problem. If a person is prone to alcohol-related problems, drinking a little is about like drinking a lot.)
He's absolutely got to get correctly diagnosed. Even if it costs cash out of pocket, he needs to see a doctor. Polyps or hemmoroids are the least of his possible problems with symptoms like that, and his life is suffering.
ps -- my mother used to drink, and she had to stop entirely. She tried "cutting back," but it just leads to more drinking. I think "cutting back" when one has been an alcoholic is about as useful for the health as cutting back is when smoking. You still get cancer even if you smoke fewer ciggies. Your son needs to go to an AA meeting.