My son has been sick since Sunday and not really eaten the past few days. He has randomly been drinking milk and eating a few apple slices the past few days. He has been spiking fevers which we can bring down with Advil. We are on vacation and he's clingy and lethargic. When do I start to worry? Or just let this pass since we are able to bring his fever down... He's 3 and never really gotten sick like this he is usually same activity level and eating habits.