As you have mentioned that your child is only 3 years old, try to avoid giving him tab. Ibuprofen
as it may cause gastritis
lead to abdominal distention and flatulence
. Only give him tab. Paracetamol
for fever and consult a child specialist to know the exact cause of fever. Try to give him small and frequent meal as empty stomach for long period may cause gas formation,avoid giving him spicy food and give him more liquid based meal.
Take care of him, bye.