R.J.
Gatorade
Or pedialyte.
Same thing (essentially). But Gatorade tastes better.
Both have salts (potassium salts as well as regular salt) aka "electrolytes", which is the big danger from vomiting &/or diarrhea. Electrolytes get out of kilter, and cause seizures (what long distance runners, athletes in the heat, and a puking kid all have in common).
Both have sugars to protect the brain that are absorbed through the mouth, esophagus, and stomach lining. (One time not to gripe that kids arent swallowing is when they have something sugary in their mouth when sick. WeWANT those sugars to absorb. And if the stomach is flushing itself out... Not a lotta time to absorb.
Both have water to he'll combat dehydration & lower fevers.
ALSO good is soda (salt & sugar, but no potassium) the carbonation helps both in absorbtion rates as well as a propellant so the body doesn't have to work so hard to vomit (bulemia trick, there). Ginger Ale is a good choice for the antinausea properties. Sprite or 7up is next best (no color).
Once food can be kept down: high fat soups (chicken or phò are our favs... Jewish & Vietnamese penicillin!!!)
Cool daml cloth over the eyes & nape of neck w/fever.
REST!!! Invoke movie days. Sleep the sleep of the exhausted. Rest & recuperate. Activity shuts down the immune system. No bueno. Its couch time.
Tylenol or Ibuprofen to help manage the pain. Liquid is best for fast absorbtion before its expelled.
Vaseline on the rectum for diarrhea ... To prevent acid burn. Stomach acid is one of the most caustic in the world. Apply before & after every time, preferably.