Baby stool color -2 month old baby.

Day -1 - found small black or dark color strings kind of things in his stool stool is yellow color . Day - 2 -normal stool . Day - 3 - Again few black strings kind of things in stool . Day -4 Normal yellow stool with black color seeds , so have given stool routine test , results shows normal . Day -5 - Half stool is yellow color and half stool is light green color with very few black seeds. Baby is 10 to 20 percent breast milk and remaining formula feed . No other symptoms, baby is active . Request advice whether these has been becos of bile or mothers hind milk ? Have attached all the pics for reference. Kindly advice , as we are in UAE . Have booked appointment with paediatric doctor on Saturday .