If you fast enough, you'll see a myriad of colors come out...lol! I've had black, green, yellow, orange, red-orange. My guess is that just happens to be the color of the old gunk that is being removed from your system that day! :)
It's great that you're feeling good. Detox symptoms come and go as your body searches for a clears toxins out of your system.
Happy fasting!
Tiffany