Bloodwork can be done to rule out other possibilities, such as low thyroid.
Sounds like a good doctor who listens and understands has yet to be found. I'd keep looking. Ask other people for suggestions on who to try.
You may tell the doctor how she was behaving. Now that she tried suicide they will watch her very closely, probably for the next 3 days. Doctors like to get input from other people who know the patient better. Patients know how to "act normal" when they know they are being observed. Other people, family, friends, willing to be interviewed by doctor, can provide useful descriptions. (Sometimes it has to be a "one way" conmunication, where you can tell them anything and they listen, but they can't tell you anything, due to privacy issues.)
This sounds terrible and I'm sorry you and your family member is going through this. It's my understanding that a suicide attempt would involve an involuntary hold of up to 72 hours. There are all sorts of laws regarding holding patients and it's a difficult thing. Do you feel the neglect has to do with their providing the pain medication (although, that's a little crazy as usually medication is dolled out very carefully. She had her own pills with her? Trying to understand what happened). Is there a psychiatrist on the floor assessing her? A psychiatric involuntary hold is usually considered a last resort. What type of hallucinations is she having?