Infants usually have yellow or greenish paste-like stools because of the small amount of food residue, but also formed, soft, strip-like stools, which are normal.
If the stool does not change much from what it was before, the baby has a good appetite and is gaining weight normally, there is usually not much of a problem.
If there is a sudden onset of unformed, loose stools or other changes in stool properties, especially if they are accompanied by crying, poor spirits or frequent vomiting, a visit to the paediatrician is recommended.