Thanks for the query
Reducing substance in stool suggest lactose intolerance. In most of the cases it is secondary to diarrhea
and transient in nature. Congenital lactose intolerance
is rare. Management is to avoid lactose containing substance in feed,. In most of the cases this restriction is needed for few days only and after that one can start it again. Weaning which you have started at 4.5 month is earlier the p[roper age of weaning is 6 months. Now when you have started weaning continue it and consult a pediatrician
for proper dietery advice.