Loss of 2.6 lbs this week! I need some insight health gurus!!!

Okay, I'm not sure what's going on honestly!  lol  I haven't stepped foot in the gym in 2 weeks, but yet I'm still losing weight.  I spent that entire YEAR in the gym multiple times a week, and didn't lose the weight that I wanted.  I now wonder if I was exercising too much or if it had something to do with not drinking enough water to replenish the water I was losing sweating it out to all that Zumba.  It really frustrates me.  I didn't eat incredibly great this week, but I still did pretty good.  I only ate out twice, McDonald's and Chinese.  I didn't get my normal meal at Chinese either, I cut back a great deal and didn't even finish it.  I also spread it out to two meals yesterday.  Yes, yesterday, I consumed a great deal of sodium - yet the scale still went down dramatically.  Crazy, huh?!?!  ;)