Lochaber nailed it. Make sure when you do your water changes that you aren't disturbing the dirt and/or cap. A cap is highly recommended. Ammonia is spiking from organic materials in the dirt you bought. Did you try to filter out the larger chunks from the dirt? Getting the fish in a better temp home would be ideal! Also make sure your dirt isn't too deep....1-2 inches max! If you're capping then 1" dirt max and 2" capping max. The more info you put out the more help you will get. Pictures always help too.