my 5 month 15 days old baby boy normally passes stool once a day or once in 2 days.But yesterday he passed yellowish green watery stool once in normal quantity and 3 times in very little quantity.In day he also did not cry for food but i gave him .he is taking formula milk. whole night he ate his milk 3 times but did not pass stool.we thought it is clear.but today morning he has passed little watery green stool.what should i do ?