All sorts of things can cause temporary weight fluctuations, but nothing will break the laws of physics. If you didn't eat 7000+ calories, you didn't gain 2 lbs.
The fluid restriction you mention is a bit concerning -- is it something your MD has put you on for a specific medical condition, like kidney or heart disease? If it's a VLC diet you're doing, I hope it's being adequately monitored and supplemented with vitamins. It's good that you contacted him with concerns and good to err on the safe side by monitoring things.
Big emotional shocks are no fun - good luck.