I don't have a specific name to recommend off the top of my head, so I wouldn't want to point you in the wrong direction. What I would suggest is to call KKH's appointment line directly and ask them to refer you to a paediatric gastroenterologist, as they have a dedicated department for that. You can also ask your regular PD or polyclinic doctor for a formal referral letter, which sometimes helps you get routed to the right specialist faster. Hopefully other mummies here have a name to share too lah, as a personal recommendation always helps more.