weight keeps going up??!

I'm a 17 yr old girl, 5' nd last week I was 116. I have lost about 20 pounds over the school year (since around October) from diet nd exercise, nothing to extreme. I actually was at a stand still for a while now (a month or so) but this week I've been gaining weight like crazy! I gained about a pound every day no matter how many calories I eat (caloriecount recommends 1200)! I admit I eat occasional junk food, last night one slice of pizza, the night before some nighttime icecream! Is tht causing this? I woke up today at 119.4! What is going on? Please help! Ps, I'm weighing myself the same time every day under the same conditions so don't worry about tht.

You can't gain a pound daily you would have to eat 3500 calories onto of what you burn. It is probably water weight from the junk just drink more water and it will eventually go down.

Your weight varies over a couple of pounds from day to day.  Don't get alarmed.

True you cant gain a pound in 1 day.  It's water weight, unless you ate well over 3500 calories.  I wouldnt follow calorie count's 1200 plan, especially since you are young.