I could be wrong but when this happened to me I was told by a friend who words for an aquatic shop that this is known as a tank crash where nitrite and nitrate read 0 and ammonia is rising he told me to do water change at 50% then add safe start the friendly bacteria to filter to recycle tank.. Hope this helps.
This is a common mistake. Adding to many fishes to a new tank. What are you using for your water source? Prime works great for FW, but you need to remove Metals, nitrate and Phos. from your source water. We do this with an RO/DI unit.