welcome to HCM,
as per the description u have given ,
most propably the child is having ATOPIC DERMATITIS
..this atopic dermatistis responds well to mild steroids..okay..as you have stopped applying the cream, leasions have re-appeared and , due to itching , child might have scratched those leasions and it turned to infection...
i advise you to use the combination of MILD STEROID +ANTIBIOTIC LIKE , HYDROCORTISONE CREAM
+ T-BACT OR MOMETASONE
THIS WILL DEFINETLY HELP U...