Acute decline in my grandmother’s health. None of the doctors can seem to find an issue/solution. Any advice?

My grandmother was diagnosed with mild onset dementia about three years ago. CT scans had shown TIAs to be the issue and she was prescribed Risperidol for the hallucinations/paranoia/delusions. She was better and off that within a month. Fast forward three years and, almost overnight, she has declined immensely with the same symptoms. The CT scan, blood tests, and urinalysis have come back all normal for her age. She is back on the Risperidol (at a higher dosage) and there have been no changes. She is still cognitive in her daily routines, always knows what medicines she should be taking and when. Things got so bad we had to admit her into a geriatric behavioral unit in a hospital and she only gets out of her room when her hallucinations have her afraid that someone is trying to kill her from the ceiling (or similar situations). She has been in there two weeks now, without any improvement. I have requested an MRI, but the neurologist only did a dementia evaluation. The medicine is no longer working, her delusions and paranoia are scaring her to death, and she isn’t sleeping well because of it. There are so many varying issues that I don’t even know what to focus on to see any type of improvement. Does anyone have any advice? I’ve suggested cardiology and neurology because I think the dementia is vascular, but because her ekgs always return normal, they see no need to further examine her. We don’t want to check her out of the hospital when she is not better, but we aren’t seeing any improvement and wouldn’t know what to do with her in the meantime if we did take her out in order to see specialists. If anyone has any similar experiences, please give me your input! We are at our wits end and it’s breaking our hearts.