Green Stool = Good Bacteria (probiotics) Not Present Inside Bowel
It is good bacteria that converts green bile pigment from green color into yellow.
In your case, flush or post flush diet flushed out all beneficial bacteria(probiotics), so your gut is bacteria free. That is not good, may cause constipation.
You need probiotics infusion ( Probiotics Enema ), or fecal flora replacement enema (infusion).