South beach crazy weight swings

I played 4 ice hockey games in 36 hours on the weekend. It was a gruelling tournament! I broke down and had 5-6 beers total (few after a couple of games). I ended up eating carbs-a couple burgers, chips. Not too bad at all.

Monday morning my weight gain was up 13pounds! Finally today a couple days later I am back down 7 pounds. What the hell is going on here? Water retention? What about the 6 hours of skating?