What to do if a four years old is frequently...

What is the treatment of repeated vomitting ?
It's important to prevent dehydration in your condition so you have to visit Pediatric department and your kid will be supllied by an IV Fluid such as normal saline , and will be given IV Pramin to stop vomitting as well as Paracetamol Syrup in case if you have fever , Antibiotic will be prescribed if Gastroentritis is present such as Metronidazole syrup in a dose suitable for patients weight 
What are the tests should be requested ?
First of all , doctor will assess presence of signs of dehydration then stoolanalysis is a must with culture , endoscope is done in case of suspension of intestinal obstruction 
What are the symptoms of Gastroenteritis ?

• Vomitting 
• Abdominal pain 
• Diarrhea 
• Fever 
• mucoid stool

Advice :
visit you pediatric doctor to do the previously mentioned tests