Woman asleep for THREE days

Patient: My aunt is around 70 years old and was diagnosed with Alzheimer’s a couple of months ago. 3 days ago she went to sleep and she can’t wake up. If she wakes up then its for maximum 30 seconds. She has been admitted in the hospital but the doctors have no clue as to what the problem is. They have ruled out; stroke, seizure, and chemical reaction in the blood due to medication. Would you have any knowledge of what is happening with her? And she is not diabetic. Please help.