My 16 Year Old Son Is Having Stomach Pains (located

My 16 year old son is having stomach pains (located centrally) for the past three days. His bowel movement is green in color and takes the shape of "stringy" like appearance. I don't think it would be an appendicitis because the pain is not on the right side but now he is experiencing green bowel movement. Should he be seen by the emergency room as it is getting late into the evening and his doctor does not have hours for the next 5 days.