Answer:
Dissociative Identity Disorder
Step-by-step explanation:
Another name for dissociative identity disorder is also known as Multiple Personality Disorder. This disorder is defined as "a condition that is characterized by the presence of two or more distinct personality states".
This means that she switches between two personalities where she becomes a completely different person. The main problem with this disorder is that her conscious state (the personality that she is more associated with) often has no recollection of anything while the other personality "takes over". Meaning that she will have large gaps in her memory from when she is not in control.
Unfortunately this disorder cannot be cured, however it is treatable to a point where a person can lead a normal life.