Hello , he could have a bad case of alcohol posioning so you chould take him to a docter.
Hi,
An allergic reaction may not manifest this way. It is more likely to cause itchiness or rash and sometimes breathlessness. It’s also unlikely that he will develop an allergy after prolonged drinking of the same substance. The symptoms could be due to vitamin deficiencies or metabolic disorders. You can consult an allergy specialist, who will do a skin test to rule out an allergic cause for his symptoms. Hope this helped and do keep us posted. Warm regards.