I think there might be something mentally wrong with my sister, she needs help?

Consult with someone. If you speak to any professional from any of the various specialties (psychiatry, psychology, social work, counseling, etc.) he or she can explain the services available and make a recommendation for you. If you see a licensed mental health professional you will have the assurance that the individual has passed rigorous exams and is at least minimally qualified to provide services for you.