Why is my chihuahua's poop green?

All I've fed my chihuahua (named Rover) in the last 48 hours is 3 soy sausages with sugar free ketchup, mountain dew, a small bacon sandwich, blueberries and double cream. But now his poop is totally green!?! This is my dog's normal diet. Please help ... Rover is now embarrassing to walk as other dog owners taunt me over the color of his poop. This is ruining my life. :(