Downton, my Nan did this it was heart breaking, she was in her own home and just stopped eating, only drinking small sips, we didn't know of any dementia, she had been fine, but for some reason just didn't want anything.
I still can't believe she just did this, I would make Complan porridge, get little treats, she just wouldn't eat it all. I used to sit and talk to her how she had to eat etc. etc. my Mum and I started to stay with her, she didn't want to go to bed, just sat in her armchair. We would help her to the toilet (similar to your Mum). The doctor said she had made a decision and all he could do was make her comfortable.
Eventually she was weak and hallucinating, the doctor prescribed morphine, we were very upset, as she was only 75, but had given up, the morphine was a relief to be honest for all of us. She passed away peacefully in the end, but it was all so horrid and frustrating, so I completely understand what you are going through,
I think all you can do is keep making a fuss and insist the doctor gives her something, there are people who are more qualified to tell you what to do, but just wanted you to know that you are not alone, in either the frustration, sadness and loss of your Mum as you knew her.
I am so sorry for what you are going through, she is lucky she has a wonderful daughter to fight for her.
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