She may be suffering from Depression. She needs a thorough evaluation.
It's wise to take the help of mental health professionals for your concerns.
She may feel better with Psychotherapy. She may also need medication according to the symptom profile, which will be temporary. They will help her return back to her baseline faster.
Next Steps
Consult a Psychiatrist.
Health Tips
Watch for any suicidal ideation. Do not delay seeking help of the mental health professional