Why is my son passing green stools?

Q: My son who is 3 months old is passing green mucous stool with a mix of yellow curd. Also, I am cleaning mucus from his nostrils too. Otherwise he is a happy child but cries sometimes. He is being exclusively breastfed for the past 3 months. Could you suggest me what is the reason for green mucous stool?

A:Exclusively breast fed babies may pass these kind of stools, which is normal, especially if he is otherwise fine and gaining weight adequately.