It is not recommended to give any pain relievers or stomach medications to a 5-year-old without a professional diagnosis, as this can mask serious conditions like appendicitis. For mild stomach upset, encourage your child to rest, sip water, and try to have a bowel movement. Avoid giving ibuprofen or aspirin. If the stomach pain is severe, constant, or accompanied by warning signs like fever, repeated vomiting, a hard or swollen abdomen, or lethargy, please seek immediate medical attention from a paediatrician or visit an emergency clinic.