I have extreme mood swings because of my bipolar which is a cycle that you can almost set a clock by...every 3 days.

Another one is Borderline Personality Disorder which is actually a triggered cycle. I feel that a lot of bipolars are actually BPD, anyway, that's something else all together.

Maybe the sad self wanted to express herself? Wanted attention? Sometimes being sad begs for comfort. Maybe ask why she's so sad? Maybe make her day?

Just guessing, but it's viable.