this is from an unknown substance. he came inside from playing complaining about "itties" (itchies) on his legs and little buns.
if he were to drink milk or eat an egg he would be covered from his nose down in these hives. picture how freaky that is. yes.
so maybe he played with acorns or touched some plant he's allergic to. but it did not do anything to his face or his breathing so he gets a bath, some anti itch gel and some homeopathic allergy medicine and then its nap time