Mum in nursing home repeating behaviour. Has anyone seen this before?

Hi wondering if anyone has experienced this behaviour in their loved ones.
Mum started to decline about 4 weeks ago - stopped eating an drinking - the last 2 weeks has seen her display these behaviours - 2 days wide awake hallucinating and eating normally, then the next day fast asleep the whole day, next day a little awake but still sleepy, then next day almost back to normal. This has repeated for 2 weeks we are really confused. The nursing home doctor says she will go up and down like this before end of life.
Has anyone seen this before?
Many thanks!