what about age of ur child.
this may be due to acute gastritis
or may be due to food poisoning
or stomach infection
. give tab ondensetron 4 mg 1tab. 2 times & tab rantac
150mg 1 tab 3 times daily if age is more than 6 yrs. if age is less than this give half of this medicine. if vomitting stop by 1 day its ok otherwise consult ur family doctor