Quick answer - probably related to what you are eating or medicine. Detailed answer - in reviewing your question, I note that you are having green stool, but not much at a time, as opposed to diarrhea. You do not mention pain or fever. In my reading, and in my experience in practice, I have found that green stool color without diarrhea, fever, or pain, is usually related to foods, drinks, or medicine. Iron, taken alone or in a multivitamin, can cause a green color. Blue or purple colors in foods or drinks, such as grape juice or grape soda, can often cause a green color. Green color stool does not usually mean serious problems such as blood in the stool (dark, tarry, black) or gallbladder problems (pale colored stool). If you are not having other health concerns such as weight loss, fevers, night sweats, pain or diarrhea, I would encourage you to watch and wait, and reassure you that from what you are saying you are probably fine. I hope I have answered your question. If you have any further questions I will be happy to help.