Gas pain after drinking
I actually did not start to have gas pains until around day 3, so it may not have much to do with your drinking. I remember the first few days thinking "People talk about how bad the gas pains are, but this is nothing." Then they hit me! In addition to the walking, I used Gas-X. They have Gas-X strips that you put on your tongue to dissolve (like Listerine Pocket tabs), so I didn't have to worry about trying to swallow pills or chewable tablets.
What you have is normal. I have them too (am 7 days post op). I make sure to eat slowly, and make sure to not overeat. Also, take a Prilosec and 4 of those Gas-X dissolving strips. When my gas got really bad, I just took some of the narcotic pain meds my doc prescribed. I don't like taking heavy drugs like that, but those gas pains are like labor pains!!! Mine have gotten better, I must say, but they're still terrible in the evenings sometimes. Hang in there.