MothersCarer,
I certainly didn't mean any criticism or personal attack on you and I'm very sorry if I worded things in a way that upset you. My intent was only to elicit more information from you about what conversational situations, if any, are upsetting your mum, or if she is just spontaneously coming out with "why do you think I have a problem?" This was just to try to understand the situation a little better so as to offer more specific advice or garner suggestions from others.
It's perfectly clear that you are a very caring daughter and only want what is best for your mother.
I am sure the past four years as her carer have been very difficult for you. This disease really is awful and those with dementia are not the only sufferers.
I am sure you are not doing anything wrong!
I have seen many other people on here mention behaviour or status changes after an illness or hospital visit, so perhaps that is part of what's going on with your mother.
My best guess is to try some different responses to see what seems to work. When she asks you, "why do you think I have a problem?" you might try:
-Mum, I don't think you have any problems, but the doctors say you need to take this medication, or use this hospital bed, or wear the emergency call lanyard. Sometimes making someone else the "bad guy," basically by shifting the blame, is an effective distraction. When my mother asked me repeatedly why she couldn't go home (when in hospital and also now in care home) I would reply, "I know you'd rather be at home, who wouldn't? However, the doctor says this is where you need to be, just for now." When she would then say, when can I go home? I would reply, "I don't know when you can go home, the doctors will tell us, but I'm sure it will be soon." And when she would ask me, can I go home today? I would reply, "I don't know, but we will ask the doctor. If not today, then probably tomorrow." And then I'd distract her with a snack or something and change the subject.
Does she repeat her question, if you don't answer, or get upset?
I also occasionally get the "I'm not stupid, you don't have to write it down, I don't need a note" sort of response if I leave my mother a note or ask her to write something down. I find that blaming my own faulty memory helps a lot in these situations. So I'll say, I know you don't need the reminder, but writing it down helps me remember, and she will accept that. Or if she starts to get upset about something she can't remember, and asks me, sometimes I will say, well, I don't remember either, and she usually laughs at that or at least lightens up.
I'm sorry this is so hard for you.