Your child having fever, loose stools and vomiting points towards Acute Gastroenteritis, probably of viral origin.
Your child would need fluids to ward off dehydration due to increased losses. In this scenario, if he is not able to drink, you need to visit your nearest hospital to get him reviewed for dehydration and starting IV fluids as necessary. Antibiotics are not a necessity and can unnecessarily prolong a diarrheal bout.
Next Steps
take your child to a hospital for review of hydration status
Health Tips
Delays in starting IV fluids if child is unable to drink is a very sticky clinical situation and needs avoiding.