My 21 month old son has been vomiting all night & morning. he doesnt have a fever or any other symptoms. he vomits any food he ingests. what could be wrong?

See below. : Most cases of vomiting in young children are due to a viral gastroenteritis or flu and will stop without specific medical treatment. Most important to monitor for signs of dehydration (decreased urination, dry lips/mouth, crying without tears, lethargy, and dark yellow urine) and prevent it by avoiding solid foods and encouraging frequent small sips of electrolyte solution. Contact MD if persists