Dear friend, what's her age, marital status and how she was about 6 to 12 months back etc are the factors need to be considered. Understanding her by forming a good rapport will soothen the path to resolve the condition. You have said she has developed mental disorder, the diagnosis, if done already has not been mentioned. She could have developed a mood disorder apparently but her personality also has to be assessed. Her teenage and family dynamics also need to be understood. It doesn't seem sudden onset to me but the accentuated psychological condition that needs counselling or psychotherapy and if needed medicines. Have a great day ahead n take care.

Hello.. Well first thing is we need to find out the cause of this sudden change in behavior.. Is there any family history? All the family should support her and try not to negotiate with her unless we find out the cause..please search in the Practo app for psychiatrist near by your area