You have given our information that cannot be interpreted nor understood without a proper history and physical examination. Further there are many people now giving you medical advice without the benefit of medical training.
Here is the best advice. Of your daughter is feeling ill she needs to be seen immediately the pulse ox could be spuriously low or high. There is no reason to ask people who you do not know what to do for medical advice. Including me.
However as a board certified physician there is only one safe answer. Immediate evaluation.
There is an awful lot of misinformation on this thread both on CoVId and other issues. So please advise your daughter to seek medical attention if feeling ill. It really is just that simple.
She is 25. Sunday went to get a Covid test because she has started feeling bad (cold symptoms and she works as ortho assistant). Has felt bad the past 2 days but questioned if it was a cold flu (though it is a weird time of year). She isn’t at a healthy weight but no other medical conditions. I gave her a pulse ox I purchased from Walgreens or maybe Rite Aid about a month ago. Sunday she was at 94, Monday 92 and tonight, according to her text I never saw, she measured 89 and spiked a fever of 100 (no fever previously)- she did the pulse ox on her pointer finger- no nail polish. Today she received a negative Covid test.
Her husband sleeps like the dead and would never pay attention to the pulse ox numbers and she wouldn’t have thought twice either except, well, I’m still mom and was hammering those points yesterday.
I had her take zinc, D, C, NAC and green tea yesterday and today I had brought her quercetin.
Tomorrow I will strongly suggest her running up to urgent care to get her oxygen tested.
I do appreciate the advice from everyone...I understand it is simply advice and a doctor will know more. It just freaked me out hearing 89 and not being able to get hold of her.