You need to do a 50% water change every day (not on Tuesday).
Today would get you to 1ppm, still deadly to fish.
Tomorrow’s would get you to .5, manageable.
Stop feeding. Just give a little bit, 1X a day.
Buy Prime. Use it as your water conditioner.
Prime will neutralize ammonia/nitrites combined if they are 1ppm or less, and only for 24 hours.
Wrap your head around the idea that water changes are the only way to save your fish.
If you didn’t add a beneficial bacteria to start, I recommend TetraSafeStart. But don’t add TetraSafeStart for at least 24 hours after you use Prime. The ammonia it binds is also the food for the TetraSafeStart .
And if you gave us the tank size and stocking we could help more.
The guy at the store told me to get pristine and I put that in today. I have a 45 gal. 3 severum, 1 geophagus, 1 electors blue acara