She has to be evaluated by a professional to come to some conclusions. The information that you are providing is very important but, incomplete. There are many factors which play an important role, environmental stimuli, thoughts, emotions, age, are some of them. Behaviour is only the resultant factor.
Next Steps
Take an appointment with a Clinical Psychologist.
Health Tips
It's better that you take it seriously, don't delay and get her assessed. Delay can lead to increase in behavioural issues.