Some people get headaches when they smoke too. Hard to say what the cause is, but if the sum of his negative effects was a headache, then I'd say that's not even that bad. That sounds like switching to decaf lol.
I used to drink a lot. It wasn't the quantity, more the frequency for me. But the withdraws I experienced were bad enough to make me pretty much quit. I would experience severe panic attacks. My doctor wanted to prescribe prozac or some shit. I declined, and chose to suffer through it. Non-stop panic attacks all waking hours for 2-3 weeks. It was rough, but I can tell you I'm a lot happier on the other side of all that.