Hello Thanks for the query This is the transition time for feeding in infants. In infancy passing stool 5-6 times a day to once in 4-5 days is a normal finding. It is the recent gross change in consistency or frequency which is important. In lactose intolerance stool reports would be positive for reducing sugar. During diarrhea there is transient loss of enzymes used in metabolism of lactose, which can lead to lactose intolerance.During this period Zerolac( lactose free formula ) can be used for few days during which resynthesis of cells used in production of enzyme occurs. After this period again breastfeed or lactose containing formula can be started. As you have already given him course of antibiotic now she needs Enterogermina respules( replenish normal gut flora lost during antibiotic therapy) 1 such daily for three days and Syp. Zincris( help to make normal bowel pattern) 5 ml daily for 14 days. The frequency will decrease within few days as intestinal epithelial cells regrow. It is not like that at this age lactose intolerance is normal. But change in bowel pattern is common in this age due to so many other factors. At this age you need to start complementary feed like starch water, dalia, suji halwa, dal ka pani, banana and smashed potato. I hope this answers your query well Wish you and your family good health With regards