Hello! Thanks for putting your query in HCM. I am a Gastroenterologist (DM).
I appreciate your concern regarding your nephew. Just relax because IBS will never harm in any way even if persists for whole life.
From the symptoms you have mentioned it seems that he is also having IBS-D, dyspepsia
, gastrocolic reflex and stress
So I will advise him to take a proton pump
inhibitor like rabeprazole
,antispasmodic agent like mebevarine, course of pre and probiotic
and tablet amitryptilline 10mg at night. See whether dairy products worsen the symptoms then please avoid it.
I hope I have answered your query and this will help you. If you have any further query I will be happy to answer that too. Remain in touch and get-well soon.