Have you ever watched biggest loser? They always say the losses are worst in the second week because your body is adapting to the new regime. Never believed it myself until I gained 1.5lbs in my second week for no good reason (well, other than I was bloated). Even though I haven't weighed in yet, I know I've dropped it because I feel it. Proof will be in the weigh-in tomorrow morning (hopefully!).
Anyhoos, I definitely believe in the 2nd week theory now, so don't let it get you down.