Here are some possibilities:
green - feed intake low, and bile not diluted
green diarrhea - Leucocytozoonosis
green diarrhea - Pullorum
green droppings capped with lge amts of white urates - Infectious Synovitis
greenish / yellow diarrhea - Chlamydiosis
greenish / yellow diarrhea - Cholera (acute
greenish / yellow diarrhea - Erysipelas
greenish diarrhea - Influenza
light yellow or yellowish green - Fowl typhoid
light yellow or yellowish green - Fowl Cholera
sulphur yellow - Blackhead
yellow diarrhea - Colibacillosis
yellow diarrhea - Ochratozicosis
yellow diarrhea - Streptococcosis
yellow green diarrhea with large amounts of white urates - Spirochetosis
yellow greenish diarrhea - Chlamydiosis
yellowish droppings - CRD
If you could: take a picture of the poop and send it to me. I can use this for further reference, especially in a death of a bird.
Send the pic to:  
[email protected]
I am serious here.
I am very, very sorry for your loss. Roos especially are hard to loose.