My doctor told me for my one child who has health issues to call if she was still doing poorly after 4 days on medicine. There are a lot of sick kids out there right now; lots of bugs. My husband, son and daughter have been sick over the last week with fevers. I am just watching for symptoms getting worse. Coughing is another part of this virus too. Keeping them hydrated and giving motrin when necessary. The antibiotic does not just leave the system once you stop. The Z pac is five days but stays in the system much longer.