I really think it's a fluke. I've been around the covid for the last 3 years coming in and out of America Korea Vietnam China all different places and I have never contacted covid. If I do have it? Maybe I just have good genes?
If she's coughing a lot make sure it doesn't turn into pneumonia. That's where it can turn into a problem.
For $20 we bought an oxygen level reader. It fits on a finger tip and gives you an oxygen and heart rate reading in a minute.