Suggest Remedy For Swollen Legs And Genitals With Rashes Due To Bug Bite

my son was bit on his leg by a bug amonth ago.imediately his leg swelled like a tennis ball.the next day it looked like a bullseye n rash up both legs,then his genitals swelled n turned purple.then his forhead swelled n eyes too.he had headaches,diahria,n couldnt walk for a few days .like arthritis,bad belly pains,n threw up too.everyday is a new symtom.today he is pooping blood.he is only 7 years old.please help.