Is this Alzheimer's progression or other illness symptoms?

Hi my mother in law has advanced Alzheimer's. We think stage 6. She was recently diagnosed with stage 4 kidney failure. She's been sleeping a lot lately, not eating much, not much urine, breathless. All the signs of kidney disease but also of possibly dying. She slept again all day yesterday and normally she sleeps through the night from 6pm until as late as 11am. Sometimes she went to bed at 4pm only to wake up at 10:30am! She only went to the toilet twice yesterday. However last night she woke up 6 times. She either went to the toilet or stood in her bedroom door or kept shouting. Each time she was fully dressed and ready for breakfast. This didn't stop until an hour ago. She kept coming out of her room and going into all other bedrooms. She said she was lost. At one point she tried to wash her lunch tray including the plate, cutlery and a cup in the bathroom. Afterwards she went round all bedrooms and cupboards again trying to work out where to put her spare tights. We are very confused as to why she acted like this in the last 24h. She has never done anything like it before and she's lived with us for a year. For some reason she thinks she lives in a residential care home as she also said that the cook told her to go in the lounge. And the other day she told me to take her lunch tray out of the bedroom so that  those who take the trays away don't need to come in the her bedroom. My question is: would this be down to her Alzheimer's getting worse or are these the symptoms of her kidneys deteriorating? I research a lot about kidney failure and the mental confusion could be down to this condition. However if I didn't know that she has a stage 4 kidney failure I would have put it all down to Alzheimer's. It's hard for us to establish whether it is down to Alzheimer's as it is happening so quick and I thought Alzheimer's was a very slow progressing disease. Any advice by those with experience of looking after someone with both Alzheimer's and/or kidney failure would be greatly appreciated.