Hi RPoornima, Thanks for writing your query. Yellowish brown colour of normal stool is because of a pigment secreted in the bile juice. If the bowel transit time is less, as seen in diarrhoea, green stool occurs as bile pigment is not able to change the colour to brownish due to less transit time. Antibiotic disturbs the flora present in the intestine and result in antibiotic induced diarrhoea. These flora contains beneficial bacteria which help in digestion and absorption of food. You should get your child examined by a Paediatrician and start a Probiotic which helps in restoring the normal flora of the intestine. I hope this is helpful to you. Thanks.