This could be depression. It can cause what feels like a physical inability to get out of bed and get going, and it can definitely cause mood swings. An individual with ADHD is 3 times more likely to also have depression. I would consider this possibility.
I would also have a conversation with her about school. Is there something bothersome to her happening first thing in the morning? Anxiety can rear it’s head in many forms, including compulsive avoidance.
After that, it could be time to discuss a sleep study with her doctor. If she’s not achieving any quality sleep, it could be quite debilitating.
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism