hives indicate an allergy. so it could be caused from anything in his environoment -- something that he has touched (aundry detergent dryer softeners soap etc. ) or breathed (dust pollens etc). it does not have to be related to breast-feeding at all. finding a specific cause is often impossible. while you were carrying your son you might have got an allergic reaction through a food. instead of it infecting you it ran to your bany and produced over the months.
my 4 month old has hives i am breastfeeding him what could this be caused from