Don't worry!!! Green stool is considered normal and it should clear up quickly. All that green stool indicates is that is passed through your colon too seriously, which can be caused my the flu, stress, meds, something you ate or it can happen for what seems like no reason at all. I can't count how many times i've had it, and if you read down all the posts on this forum, you'll see that your question is very common. Shouldn't be anything to worry about!! If it continues for a couple weeks and is accompanied by diarreah or cramps or anything, then it may be a type of infection, but its still nothing serious. If it continues for two weeks then i would see your doc about the infection, but my guess is that it will clear up any day.
I hope i've helped!
katie