A general rule of thumb to remember is that if the body is having to go through any kind of stress (be it just TOTM or a nasty cold) it will retain water as part of its physiological response to what it needs to deal with.
Remember: water is heavy, and if your body is holding onto water then it will weigh in heavier BUT that doesn't mean the weight is fat, and unless you start eating more calories it is highly unlikely you will have gained body fat.
Give your body time to get over the stress, it will then jettison the water and you will be seeing a much smaller number on your scales than before.
Also, when you're ill your metabolic rate is put up - meaning more calories burned and an even smaller number in a few weeks time when you've recovered and stopped feeling snotty!
Keep your eyes on the prize, and don't let a few bum numbers put you off. Weight loss is a little like playing poker - a professional poker player can be up £2500 one minute, and then down £5000 the next; you won't catch any of them giving up at the first sign of a big loss though. For them it doesn't matter what specific gains/losses made in each round of a game as long as at the end of the game they've got a positive total to take to the bank. They play the law of averages - sometimes they're up, sometimes they're down, but as long as the averages over the entire game shows them going in the right direction then they'll keep on playing.
For instance, micaleff, looking at your losses, you've lost an average of 5lbs a week. That's amazing! So what if one week it's no weight change and another it's 11lbs? That's just demonstrating that your body was taking on (heavy, but not fattening) water for a short while of its own accord.
When in doubt, look at your average!