Thank you for your query,
Your child seems to have a Viral illness with Gastritis
The running heart is due to fever.
every 8 th hourly depending on the presence of fever in prescribed dosage and do tepid sponging with lukewarm water.
Give adequate rest and give plenty of oral fluids and if the nausea is severe, you can give anti emetic like ondansetron
in prescribed dose.
Consult your Pediatrician
for the examination and management.
Hope I have answered your query.