Feeling nauseous by itself is not a symptom of an allergic reaction, and the CDC recommends avoiding a second dose in a patient with any allergic reaction within 4 hours of the first vaccine injection. In the case you present, the rash appears to have started more than 4 hours after the first dose. In this case, the second dose would not be contraindicated per the CDC guidelines (although she may develop a delayed rash again after the vaccine). I do wonder if she had a fever with the nausea and diarrhea, as her symptoms sound more like she had a gastrointestinal virus (and associated rash) that just happened to occur around the time of the vaccine.
I hope this is helpful.
Mitchell Grayson, MD, FAAAAI