Bipolar II here (yeah turns out Bipolar was so good they made a second one)

Personally it doesn't sound like they went fully manic (else you or them would've been in greater danger), but instead it sounds like a mood swing. When unmedicated, it is too easy for the smallest of emotion to trigger a meltdown. A slightly irritating thing means uncontrollable anger, a slightly sad or pitiful thing means uncontrollable depression (emotion) and crying, etc.

I've had days where I feel completely hopeless and filled with despair, crying and giving up on life, only to realize I've forgotten to take my pills in a couple of days, and be so much better to the point that it feels like it was another person expressing that desperation a couple of hours later. It's honestly very interesting (if you set aside the worrying aspects) to see how a brain can change so abruptly