I Am Trying To Find Information On Some Symptoms That

I am trying to find information on some symptoms that my grandmother began exhibiting this morning. My 79 year old grandmother lives with my father. Other than chronic back pain from previous injuries, she has shown no signs of recent illness. Last night my father checked on her at bed time, had her take her usual meds and everything was normal. This morning at 6am he went in to wake her and she was non responsive. After several attempts to wake her, he called an ambulance and she was admitted in hospital. When she arrived she was able to respond to simple questions like her name and birthdate but will not open her eyes or stay awake more than a few seconds. She responds to pain (being moved from bed to bed), wakes long enough to tell the nurses that she needs to urinate etc. but immediately falls asleep again after getting the words out. She woke twice to say that she was hungry but can't stay awake long enough to eat anything. CT scan showed no evidence of stroke and they can find nothing wrong with her at all. Yesterday she went about her normal routine, watched TV, walked from room to room in the house, ate normally and had conversations with the family. Today she seems to be in a minimally conscious state for no apparent reason. I am hoping to get some ideas as to what might be wrong.