What Causes Green Stool And Stomach Ache At Night?

Hello, I ve been having green stool for the past 3 days. My stool is regular for 2 weeks, and then the next 3 days it s green, almost a pattern. I thought of a tapeworm as well, my stomach tends to ache a little bit towards the night, closer to my bowel movement. Not really sure what s going on.