I had a similar problem a few years ago.
Just about every time I would drink anything hard, I would vomit blood. I also went to the hospital at one point. (That whole bloody vomit thing gets kinda scary after a while).
Basically, the deal with me was that my stomach didn't like the Jack Daniels as much as I did. I could drink liquor just fine for a number of years until, all of a sudden, my stomach couldn't handle it anymore. I had to stop drinking liquor.
I'm perfectly fine and healthy, I just can't drink liquor. I can drink beer without any problems, so I just stick with that. (In moderation, of course).:angel2:
I wish you and your son well.