a few weeks ago dd2 had a really bad nappy rash and diahorea, didnt really think much of it but had to get her a prescription for it as it took over a week to go.
This morning my mum admitted that she hadnt realiased baking poqwder had gluten in it and dd1's gluten free cake had baking powder init, we dug out the cream and the date was exactly a week after dd1's birthday. No further experiments needed then.