My daughter has a red rash that comes and goes?!

LAst week she had an ear infection!. She was on antibiotics!. Saturday I woke up to her having a fever and she threw up she had bright red arms and legs!. I gave her antihistamine thinking maybe she got bit by something!.!. I gave her a bath with baking soda!.!.!. It went away!. She laid down to nap and woke up with a rash that looks like hives!. It goes away and comes back while she sleeps like this morning it is only on one arm but it is disappearing!.!.!. She has been having a low grade fever on and off!.
I thought maybe scarletina but I looked it up and this does not seem like that!.
I will be taking her to the doctor tomorrow but wonder what I should do today!. She is not in pain and is acting totally normal!.Www@Answer-Health@Com

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