Hello new obsession

I knew I never should have hopped on the damn thing 3 weeks ago. But I've started a new cardio routine, and am really trying to watch my diet.
I was thrilled to discover that the weight I had lost from being a desperate heart broken maniac has stayed off.
Then..............well, you can guess. Now I've decided that not only will I stay at this new weight, I will make it a goal to lose 10 more.
Yesterday morning I weighed in at 131. This morning, 134. How the hell does a person gain 3 lbs in a day?!?!
Hello new obsession............