Did I really gain 2 pounds in 2 days?

Ok, so these past couple days, I've eaten very unhealthy. I had to help run a pizza booth for this fundraiser my youth group had, & the only thing we could eat was pizza for lunch & dinner, unless we wanted to pay like $10 for a meal somewhere else. Well, I found out that just one of the little personal pizzas, which is what I had to eat 2 of, had 590 calories &, like, 30 grams of fat each. Then, there was another booth next to ours that was selling funnel cake & I sort of gave in & got one. I split it with a couple friends so it wasn't AS bad, but it was still unhealthy. Even then, I figured up my daily calories were roughly 2,000. Then the next day, I ate a ton of Girl Scout Cookies. I figured it all up, & I found out I had eaten 25 grams of saturated fat. Ugh. But even then, I ate about 2,000 calories. So I weighed myself today & since about a week ago, I gained 2 pounds! Is this water weight? I mean, those pizzas were pretty high in sodium. Will my weight go back to normal once I start eating healthier again? I'm just really scared, because I lost about 30 pounds, & I don't want to gain it all back again. This was how I used to eat before I lost the weight, & I'm worried I'll realize how good junk food tastes & eat like that again. Maybe I'm just paranoid. Oh, & no rude comments, please!