Provide differential diagnoses for Jo and Riley with rationale?

Discussion Part One (graded)

Today you note that both Jo and Riley are on your schedule for ill visits 4 months after your last visit.

Current ages: Jo – 6-year-old female, Riley 24-month-old male

HPI: Both children have had several episodes of vomiting over the last 2 days and have developed diarrhea in the last 24 hours. Jo has not vomited today, but Riley vomited twice this morning in small amounts since awakening. They have both had low-grade fevers of around 100 to 101 degrees in the afternoons. Mother reports that both have not eaten solid food since 36 hours prior to this visit, when they went to a pizza buffet in a town nearby. They have been keeping down some sprite, apple juice, and popsicles. Both urinated this morning. Mother has given both children Pepto-Bismol over the counter (OTC) to prevent an upset stomach and liquid acetaminophen two to three times a day for fever, but she reports that Riley vomited soon after his dose this morning. Jo has also complained of severe lower abdominal pain beginning last night in the middle of the night. There are no other associated symptoms.

PMH: Jo is continuing on Ritalin, 5mg daily since you began her on this several months ago and is doing well. She has not had medication in the last two days. They both have been well since their last visit.

Discussion Questions Part One:

Provide differential diagnoses for Jo and Riley with rationale?

Further ROS questions needed to develop the differential diagnosis?