Jordan is a 4-year-old with a 1-day history of vomiting and diarrhea. His mother reports he awoke this morning vomiting and his vomitus contained last night's dinner. He vomited three more times this morning but has not vomited in 5 hours. Approximately one hour ago, he had a large diarrhea stool that did not contain blood or mucus. He has had small sips of sports drinks since this morning. His last urination occurred 3 hours ago and the volume was small and the color dark yellow. Physical examination reveals a quiet and tired child with normal exam except for increased bowel sounds, but no abdominal distension, pain with palpation, or masses. what are the differential diagnosis for this individual