Don't weigh daily! Your body fluctuates alot during the week... you may have eaten something salty yesterday & retained water?
You've posted that yr constipated... that will make a difference too! You have still lost 2lbs so far & yr week isn't over yet, hopefully if you can sort out the constipation today & guzzle lots of water when you weigh in tomorrow you'll have an even better result than the 2lbs you've already lost!!
Unless daily weighing doesn't affect you & by that I mean the fluctuations then hide the scales & weigh in once a week... then you'll have good results!!
It's probably water, and yes that's the perils of weighing daily. Back in the day when I was a scaleaholic I could gain and lose 3lbs during the course of the day.
Will definately have to try and keep myself off the scales everyday, i'm a scale-a-holic but get disheartened so quickly so must try to weigh only once a week, it's hard though isn't it???