Sounds like RSV
Well, there has been a lot of cases of that at this time.
However, when I read her symptoms, it sounded a lot like what happened to me during the summer this year. It started with having trouble breathing. I ended up in the hospital for days. They had to transfuse three bags of blood into me. Doc later told me that I had "Severe Anemia". There is anemia and then there is "severe anemia". I am finally beginning to feel better. It really knocked me out.