Nitrite Gone Wild

[Confetto]

I use Tetra Easy Strips 6-in-1 to test my three gallon tank. Last Weds, I dosed my plants with Aqueon Plant Food. Thursday, I had a spike in my nitrite levels - expected however I went from 0 to danger (10.0ppm). My nitrate levels also went from 0 to stressed (80ppm) and my pH had dropped to 6.2 

I dosed the pH with Imagitarium's Enhancer once and we're back to 6.8.  Friday I did a water change (25%ish) and my nitrite is still holding at 10.

Today I did another water change and nitrate is measuring in the safe zone around 20ppm but nitrite is still bonkers.

What am I doing wrong?

Miso is doing OK. His activity is the same. In fact he's busy making a bubble nest. I have a few yellow tipped frogbit leaves, and my anubias look fine.

Stats: 

pH: 6.8  Alkalinity: 0/low. Chlorine:0. GH: 75/soft. Nitrite: 10.0. Nitrate: less than 20

[Colu]

What is would do is stop add pH enhancer and just add some crushed coral to help slowly raise your ph what I would do is daily 50%water changes and add a double dose of prime to help detoxify any nitrites till they constantly stay at zero you can also add some aquarium salt  1table spoon for 1gallon will help prevent mathemoglobin toxicity by blocking nitrite adsorption though the fish Gill's