Good behavior, but my weight is going up

This is frustrating--I've been good the past couple of days about sticking to my meals and not snacking constantly, and the Christmas goodies are all but gone (down to just some gingerbread cookies and cherry candy canes, which I think are gross), and I exercised yesterday and on Tuesday I did the non-exercise-but-still-active evening routine (where I don't let myself sit down but instead keep moving all evening doing household stuff and generally get a lot accomplished) but my weight has been up the past two days--138.4 yesterday and 138.8 today. Yuck. Maybe I should try some fat flushing or South Beach or nicotine patches until I drop eight pounds! I'm also noticing that now that the weather has finally turned cold I'm really thirsty all the time, so at least I'm drinking a lot of water, and maybe, with any luck, that's why my weight has gone up! OTOH, I guess I'm thirsty because I'm getting dehydrated, so I suppose that all evens out.