Willie is right, your daily weight fluctuates a lot, and often for no apparent reason. Many of us are daily weighers - for me, it keeps me on track. I know that when I stop weighing daily, it's because I know I've not been eating/drinking as I should. But - you do have to get used to the scales showing a gain as well as a loss!
And it may seem obvious, but presumably you are weighing yourself first thing in the morning, naked, and before you have had anything to eat/drink (and ideally after you've been to the loo!)?
And it is only Tuesday!!!