So sorry for the late reply, and thank you for the suggestions. Yes, I'm possibly over-thinking it too much, I'm just worried if there's an underlying problem that makes lactose intolerance secondary. I find it a bit puzzling she seemed fine on cow's milk yoghurt. I'm in Australia, that's why it is a long wait for a consult with any paediatrician. However, I've managed to get an appointment for the 9th March. Will stick with the lactose-free diet for the moment.