I would tend to think, if you are just now getting the ammonia spike, yor nitrites/nitrates haven't caught up to the ammonia (does that sound right?)
What other fish do you have in there and can you take them back to the LFS
(if your tanks hasn't finished it's cycle)? You might lose everything in the tank, if you have inverts in there as well....
I am guessing you took advice from your LFS
? Don't worry, a lot of people do. That is why this forum is great. There is more experience here than any LFS
. What did/do is ask a lot of questions, here, and read. My LFS
hasn't steered me wrong, but I still ask here first.