My daughter was diagnosed just before her 5th birthday, but had symptoms the doctor insisted were nothing since she was 3. So sounds similar to your grandson.I know the drill; my now eight-year-old grandson has VEO-IBD and has been going for monthly infusions at Children’s Hospital of Philadelphia since he was three. Missing one isn’t good. Hope that if your daughter has to miss this one, they’ll get her rescheduled very quickly.
Her infusion center is pretty good about rescheduling - but she feels it when she is delayed for as little as a week. I would be surprised if she has symptoms by tomorrow - and her night shift job means we aren't in the public parts of the house much at the same time.