Hi welcome to HCM... Your small child having diarrhea since week approx... It could be enteritis like infection....It can be from viral , bacterial or parasitic infection ... Here your child were given broad spectrum antibiotic course .. Still not improve much so stool routine microscopic examination and if needed stool culture can be done ... If it shows parasitic infection than treated accordingly with anthelmatic drug ... If still cause not found than USG done for further work up.. Meanwhile maintain your child s hydration... Take care Advise : pediatrician or gastroenterologist consultation ...