Help!

I did a ~75% water change 2 days ago to get rid of some algae build up. Didn’t test the water yesterday. I woke up to my fish acting funny and this is what I saw (Ammonia, nitrite, nitrate - in that order)

I’m not sure why the water got so bad so quick. I’m doing another water change now. I don’t want to shock her. How much water should I change? And anything else I can do to make sure she survives?