My 3 year old son has been lethargic since Wednesday night. He vomited on Wed night. Woke up Thurs, ate a small breakfast and slept all day. Thurs night he vomited while brushing his teeth. Friday he ate a great breakfast but was less active than usual. He ate a good lunch and took a great nap. After his nap he was very lethargic and just wanted to lay back down. He vomited in the evening. Today he was normal in the morning - eating a good breakfast and lunch, but after nap he was very lethargic again just wanted to lay down. He has not had a fever at all. I was just wondering if this sounds like something that needs to be seen or it if sounds like a stomach bug that should pass on its own.