Hello! Thank you for the query. Food poisoning can be caused by bacteria or viruses. Antibiotics are effective against bacteria, however are inactive against viruses. That is why your husband havent seen any difference after antibiotics use. It is also possible that his symptoms are caused by gallstones or peptic ulcer and not associated with a meal in the restaurant. Especially if his pain is in the upper middle or right abdomen. And as he is not any better, I suggest him to visit a doctor once again. He should have abdominal ultrasound, blood work and stool tests. If nothing will be found, gastroscopy should be considered. Hope this will help. Regards.