Question about teens with DS and depression

Hi, I have been working with a 12 year old girl with DS. I have been assigned to teach her in her home because several months ago she transformed from being sweet, calm, and compliant to being aggressive, violent, and unfocused. She would go days without sleeping and became very withdrawn from her family. Her quality of work and life has greatly decreased, she was once able to write her name and color a picture with attention to details, now she just scribbles her name and colors her pictures quickly with one color. Her mom has taken her to well renowned doctors and facilities with no answers. They did find a shortage of white blood cells but besides that no explanation of what was causing the withdrawal and aggression.

Has anyone been through this? I would love to help her mom in some way, she seems very overwhelmed and tired since she has been staying up at night with her. Thanks for listening.

JennyBug15