Respected user, hi I evaluated your query thoroughly .
* His condition is due to 
calamine causing 
gastritis & 
gut flora alteration .
* Nothing much serious but take some necessary steps as 
- give combination molecule of 
proton pump inhibitor with anti emetic 1 
  hour  prior to breakfast & dinner 
- plenty of liquids in sessions preferably boiled water, coconut water, lemon 
   juice , green tea, coffee , butter milk etc to maintain hydration
- small amount of light diet at regular intervals
- maintain his BP , blood sugar levels
- pre pro biotics in case of more loose motions help 
- avoid 
smoking / alcohol 
Hope this clears your query .
Welcome for any further assistance .
Thanks for using Healthcaremagic.com & giving me an opportunity to assist
Wishing him fine recovery from the same .
Regards dear take care .