Thanks for posting your query.
Your son is most likely suffering from acute bacterial gastroenteritis
Presence of abdominal pain
with fever suggest the diagnosis.
You should consult with pediatric physician and should go for thorough examination.
Throat involvement appears to be least.
You should also go for ultrasound
imaging to rule out appendicitis
Your son should take complete antibiotic course along with antispasmodics for getting relief.
Dr. Mayank Bhargava