Hello, I Was Curious About The Green Stool I've Been

Hello, I was curious about the green stool I've been passing for a few weeks. I spoke to a gastroenterologist about this issue and said I possibly have an ulcer. He removed a few hemorrhoids that day and sent me home and have been looking for a new doctor ever since. My stool has almost reached the color black; just a few shades away, but that has only happened twice. Now my girlfriend and I are both passing green stool every time we use the bathroom. We've also been enduring uncomfortable pain in our lower intestinal region. Any thoughts on why this is happening?