Few thoughts on how this thread has gone.
If a guy is going to dismiss advice, why ask?
Add me to the ones that told you your tank has not fully cycled.
Your dechlor choice will still take chlorine/chloramines and detoxify it for your emerging bacteria to process. Most all of the available products do.
Got sick fish, I`m not surprised.
The shocks that go with a with fish cycle is the loaded gun a guy plays with when doing it this way.
Adding additional bio media won`t do much, if anything at all to help. Your nitrite munchers are still in the process of establishing themselves.
Again, I agree with those that have advised time and WC is the answer to your nitrite level.
Obvious, your bacterial additive did less than a stellar job trying to instant cycle your tank.
Just a gut feeling, but I think your tank is doomed.
Honestly hope you prove me wrong on that, but with all the things your throwing into the tank and playing with temperatures, well
..
I really do hope you make it through this mess, without a complete die off or fish that have been so thrashed they will never fully recover.
Good Luck, your going to need it.