The symptoms you mentioned are suggestive of allergic reaction
The symptoms may be limited to vomiting only. But, may progress to diarrhea, exacerbation of atopic eczema
, asthma, urticaria (hives), angioedema
(swelling of the lips, face, throat and skin), acute abdominal pain
and most dangerous - the anaphylactic shock. Severe cases need hospitalization and intravenous fluid, steroid, respiratory support and other treatments.
Go to emergency room now and get your child examined NOW.