I can offer some general insights.
Personality and mood can be influenced by various factors, including genetics, environment, life experiences, and hormonal changes. Adolescence and young adulthood can be a time of significant emotional and psychological growth, and some mood swings can be a natural part of this process.
However, if the mood swings are interfering with everyday functioning, relationships, or causing distress, it may be essential to seek support from a mental health professional. These extreme mood swings and different personalities could be indicative of an underlying mental health condition such as bipolar disorder, borderline personality disorder, or other mood-related disorders.
Early intervention and proper diagnosis can make a substantial difference in managing and improving mental health. If you or someone you know is experiencing these symptoms, it's crucial to encourage them to speak with a mental health professional for a comprehensive evaluation and appropriate guidance. Remember, seeking help is a sign of strength, and mental health is just as important as physical health.