Check the bottoms of her feet carefully for a dark spot, where a small injury could have allowed a bit of infection to develop inside the foot. Do a search on bumblefoot. It is easily fixed, but it does need attention. It is just soil bacteria, often staph. And yes it is a bacteria that people can get, or actually, often already have on our skin. Your son should be fine if he has learned good handwashing after handling chickens.
