DD is 7 and has a pretty bad cough but is fine in herself and still wants to go to her swimming lesson tomorrow. You're probably thinking after 7 years I should know what to do, but she never usually just gets a cough, when she's ill it's often a fever, sickness, the works so she's too ill to go anywhere. So I don't really know what the correct etiquette is in this situation (if of course she doesn't become unwell overnight).