Like most other people on this planet, I have gotten my cases of colds, flu, bronchitis, pneumonia over the years and in every case I was able to focus on when I would get better and so had an easier time of things because of it.
With dementia though, those same simple illnesses can feel like cancer or something. First problem is if your cognitive far enough gone, you don't understand what is happening to you. Some part of you might hear your caregiver or other "adult in the room" explain that you have a cold and must simply get over it. Maybe. What is for sure is the fact (to you) that you have never felt symptoms this bad before and have a hard time accepting "a cold" as a diagnosis.
The cognitive dementia I experience seems to like me so much, it brought friends in the name of the aphasia getting way worse in correlation to how bad the overall illness feels. The other friend comes in the form of complete loss of sense of time. Because of that, you might be 4-5 days into your illness and to your mind, you don't recall a time when you *didn't* feel like this. It feels like this has gone on forever and will probably continue to go on for the rest of your life.
Grappling with stuff like that when you are already working with one hand mentally tied behind your back can and probably will only twist your mind even further.
A final coup de grace is when your only caregiver is down for the count right along with you....and if you don't have some extended levels of support from friends and family, the two of you are stuck in a no-win situation.
What makes this all fun is the fact that the worse your physical symptoms become, the worse your seemingly-unrelated dementia symptoms become. Just a fact of (my) life. My aphasia gets so bad I can hardly make myself understood sometimes. My sense of balance is all but gone, I can barely understand what I read, if I even can read at all. This makes telling doctors or even your caregiver what is wrong a task not unlike juggling chainsaws. At any given moment you might check your short-term or working memory to see how bad it is.....and after 14 days of this, your short-term memory looks like a dusty, empty bowl in your head. Not just empty of thought but it looks unused in a very long time.
This all just happened to us; we came down with bronchitis just as we got the floors replaced in our house and were bed-ridden for 10+ days. Came down with it a few days after staying at the hotel and am just now crawling out of it. Hope this never happens again in this lifetime.