My dog has a very serious aggresion problem...what can i do?

my 1 year old female english springer spaniel Angel has been attacking people and barks very aggressively today she tried to attack a three year old boy we put her to the ground and smacked her and she tried to fight back with us and continued to growl and bark and in the ped has tried attacking grown men and even some women what can i do ? Idon'tt want to give her away i love her to much idon'tknow how to stop it if you have questions please e mail me