Ay, green poop with a cough can sometimes mean a tummy bug or the milk isn't sitting well, especially if it's a sudden change, definitely worth checking with your pedia to rule out anything, kasi two months pa lang si baby at mas safe na lang makita ang doctor! A few of us had the same thing with formula changes, kaya siguro din i-monitor mo kung may other signs like fever or kung sobrang dami ng beses mag-poop, but the cough + green stool combo is something your ped should look at talaga.