DS(3) has been a bit under the weather for a few days. He's been off his food, quiet (most unusual) and has felt warm (but the thermometer says he doesn't have a fever). He's also had a few red spots on his chin which seem to come and go. He has already had chickenpox and is up to date with his vaccinations. He's perked up a bit since his brother arrived home from school and is showing a bit more interest in food. I don't know whether I should send him into nursery tomorrow, or keep him home. Any ideas what it could be?