Depression. I do next {out of the blue}

I understand your concern. Your sister seems to be suffering from adjustment problems with depressive symptoms. More clarity is needed regarding her problem. Information regarding her energy and also concentration levels would be more helpful to decide on severity of the condition. However 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.