Weight & Health Issues

Okay, I was going to go workout when I made the mistake of stepping on the scale. I did that because I feel huge. I was right, I am huge. I don't understand. For the last 6 days I have been working out and watching what I eat. Yet I am now 3 lbs higher then I was 6 days ago. Yes, I know, I did not eat enough to gain 3 lbs in 6 days but what's going on. We did go out to dinner yesterday maybe I had to much salt or something? I did have a glass of Sangria, maybe that's it?? Maybe I'm not drinking enough water. I haven't been tracking that as closely as I should. In fact, I don't remember drinking any water yesterday. Okay, I'm starting to feel better. I realize it has to be some 'outside' influence. I've been eating 1600-1800 calories a day. That is no where near too low so I think that's okay. I have been working out regularly and burning around 2500 cals, so mathematically I should be losing weight. Okay, Okay, I'm going to focus for the rest of the week and finish out my 10-day kick start plan. I'm not going to give up because I do not like this feeling.