Hello! Thank you for the query. Your husbands recent diarrhea has been most likely caused by viral or bacterial infection of the gastrointestinal tract. Every infection of the intestines caused some problems with natural intestine bacteria which constantly protects us from infections. If the pathological bacteria will find the way to take control over the intestines, the good bacteria are getting destructed. If those good bacteria wont get recovered, it may result with symptoms like your husbands. Moreover, stomach could get irritated or even peptic ulcer could get triggered during this infection. Quite often, bacterial diarrhea turns into a chronic infection leading to an IBS. That is why I suggest you to try Rifaximine 400 mg 3x1 fpr 7 days treatment (prescribed by your doctor) along with probiotic 3x1. If such treatment wont help, stool tests should be done and gastroscopy considered. Hope this will help. Regards.