My daughter has gone through a lot of trauma lately, and had a very stressful experience today.
At bedtime, she suddenly said, "you're not my mummy. You are doing such a good job of copying her!" And then asked questions that only I would know the answer to. She seemed sincerely frightened that I am not me, and cried for a long time. She still wanted me to hug and comfort her. This all went on for an hour.
She later calmed down and clearly was comforted that I really am me.
This has happened once before.
What should I do?