Hello,
Pain abdomen with persistent
diarrhea is commonly indicative of food
poisoning,
stomach flu, IBS, crohn's disease,
malabsorption syndrome, liver disorders, UTI, kidney disorders (kidney infections, kidney stones), etc.
Since he has a history of
listeriosis, you are suggested to take precautions in food & drinks, always give him food that is well cooked, boiled food will be better.
Avoid giving raw salads or fruits. He can take fruits that is cooked in oats, porridge, custard, etc. He should always take boiled water.
You are suggested to get him clinically examined by a GP. Get all the blood tests, liver function tests, Urinalysis(R/E & C.S) & investigations (X-ray, CT,MRI) done. His treatment will depend on the pathology detected.
In the meantime take anti diarrheals, antacids for relieve. Help him stay well hydrated. Cut on addictions if any.
Hope I have answered your query. Let me know if I can assist you further.
Take care
Regards,
Dr. Nupur K