Get the Prime, it will render the ammonia harmless for 24-48 hours.I've been using the Aloe Vera for a long time, so it's a definite possibility.
I'm testing my tap water and yeah, the water has turned green! I never thought of doing this. So I've been putting ammonia back into the tank, when I do water changes. Nothing comes up when I test the tank water, though.
And no white stringy poop, just normal fish poop.
You may need to cycle your tank, as well.