Ammonia/Nitrite spike in QT

After spending 5 weeks cycling my QT all the levels dropped to zero. I ordered a fish online and the moment the fish arrived the ammonia jumped back up, so I did a water change right before I put him in. A few days later it spiked again and I did another water change, just tested it now and not only is the ammonia up but the nitrite jumped as well, both are at .025.

I have only had this fish in quarantine for a week and a half, I am not looking to jump the gun but is it better to put him into the main tank or risk keeping him in the QT that I now cannot control.

He is a tiny Caribbean Tang and the fish in my main tank are a pair of Clowns, a Flame Angel, Watchman Goby and a single Chromis.

 

What so you have in the tank for sand, rocks, or filtration? How big of QT?

 

I peice of LR and 29 gallons...............real question is do I need to get this fish out and into the main tank