It never occurred to me this was happening to so many others. DD8 has this issue nightly. It's either cries of "I'm scared" or "my tummy hurts" and doesn't end up sleeping until 10PM or later. It's odd how her tummy ache suddenly starts, according to her, about half way through her last nighttime reading.

I'm going to try that melatonin therapy.

I got her a kids' book about not worrying which she liked and she even made and decorated the worry box, but she just won't use it.