Hello dear
Warm  welcome to Healthcaremagic.com
I have evaluated your query for your husband in details  .
*  The issue seems due to intestine infection with systemic manifestations
    giving fluid 
electrolyte imbalance .
*  Primary guidelines till he meets his doctor for vital parameters 
    assessment :
Consume plenty of liquids  in form of boiled water , lemon juice , coconut water , home made juices , organic  tea , coffee , butter  milk  etc .
Prefer soft , light  , bland , vegan  diet  with fresh  curd  preferably .
Avoid  all types of  oily , spicy , non veg , hot beverages , junk foods , dairy fat , milk  , aerated drinks  till recovery .
Intake of PPI  ( as 
omeprazole ) , antibiotics  ( with 
metronidazole on pack ) 
Racecadrotil as an anti secretory agent  help faster recovery , which requires prescription with your doctor .
Hope this  will help  to clear your doubt   .
Wishing him fine recovery .
Regards .