I understand your concern towards your sister. She seems to be suffering from few depressive symptoms. However more clarity is needed regarding her problem. Information regarding sleep, hunger, energy levels, interests and concentration at whatever she does would be more helpful to decide on severity of the condition. Her personality traits need to be evaluated in detail as well. It is easily manageable with appropriate treatment, so that dysfunction due to the same can be reduced and her quality of life will improve. Some counselling sessions and if needed medical help might be useful for her. I would also be more than happy to help you with that if you are looking for online assistance. Discussions will be held confidential. You can directly consult with me through Practo as needed. Online chat consultation is available.

Consult a clinical psychologist.