Green stools...if not the result of something you're eating or drinking...are the result of increased toxicity....often old bile that is being thrown off by your body.
One to two bowel movements a week is not good...major toxic build-up! Ideally you should have 2-3 bowel movements a day!...or whenever you eat a significant quantity of food. We are designed for one meal in, one meal out...much like a dog or baby.
Sounds like your body is probably unloading a lot of old toxins...keep it flowing!
You might also consider a series of liver flushes...that will help to clear out even more toxins and old, nasty bile...probably a lot of stones too!