My Wife Finished A ZPac On Thurs Or Friday Last

My wife finished a ZPac on Thurs or Friday last week which was prescribed by her doctor due to a chest cold/flu and then this Tuesday she was scheduled to go to the dentist who told her to take Antibiotic pills he prescribed and she now has diarrhea and is vomiting. Is the diarrhea and vomiting due to her cold/flu not being over or could there be an issues with taking too many antibiotic pills in a short time?