Not pregnancy related: Veteran mommas

Lindsey • Mommy to 3!
Any advice on getting a 2 year old through a bout of the stomach flu? My son has been puking non stop all day and also has severe diarrhea...I've been pushing fluids but he does tend to throw most back up. Pediatrician said if it goes past 24 hours of not holding fluids down then to take him to the ER. Any advice? Tips? Remedies?