Perhaps she is affected by transitions. Bed time, meals, arrival at a place, leaving a place. This would not be an 'overnight' thing, but more likely a development as she is becoming more cognisant as she's developing. Speak to her SendCo at school, any worth their salt will observe and ask their LSAs to break it down with pre-preparation and expectation setting then walk her through it to allow her emotions to catch up with her as the transition takes place. If it doesn't occur at school, it may be that she's holding it in, but those professionals should still be able to coach you in how to manage transitions.