Hi there,
The limited information that u have shared here definitely points towards an impending disability due to pent up psychological stress. She is not able to share her emotions probably for two reasons. One being that she thinks ppl will judge her for sharing........ or second, that she thinks the issue is hopelessly unresolvable so no point in bothering u.
Next Steps
If this is just a temporary thing and she seems to get better in coming week then it's fine... Encourage her for overcoming whatever the issue was.... But if this persists and she refuses to acknowledge this.... Then plz consider taking an appointment with a psychiatrist / psychotherapist of ur choice. They will do the rest that needs to be done.
Health Tips
Please rule out any possibility of any sorts of abuse. Children often are not very open about discussing those things.
Hope this helps... Feel free to connect in case of any further queries