Hello doctors my son is 9 months old now . Generally his stool is normal mustard colour but for the past two days his stool is very dark brown. First it comes out as dark brown then it comes as normal mustard colour . His weight is 8.7 kgs and he's very active . He's on exclusive breastfeed and solids ( vegetables dal rice ) and sometimes nestum rice . He has no pain when passing stool he's not fussy . What could be the reason? Attaching photos for your reference. He takes his vitamin d everyday and not on any other supplements