Weight gain?

I was about to watch Brokeback Mountain on Netflix, but I wanted to post this first. So I feel like I may be gaining weight again. I don't know. Most mornings I'm one hundred and seven pounds, and by the end of the day I'm pushing ten. Is that normal? Are you supposed to gain that much during the day, a whole three pounds, and then lose them overnight just to gain them back? Plus I feel like my stomach is poking a bit too much again but I don't know maybe I'm just being paranoid. I wish I could just stay at 105 pounds like I was over the summer for about two weeks. Those were the happiest two weeks ever. I felt on top of the world.