Take him to the emergency room.
Cool him off with wet rags.
It could be appendicitis
Welcome to the gastroenterology community! It might be an appendicitis. If it was just a stomach virus causing the pain he probably would have had diarrhea or vomiting. Even though the appendix is located more to the right, the pain can something be in a different place. I would recommend taking him to the ER asap and asking for a CT scan with contrast of his abdomen. Good luck.