To me, it seems that the additiong of more liverock kicked off another cycle in your tank. This is indicated by the slight ammonia and nitrites. Both of which are very toxic to animals.
Since you don't want any of your other creatures to die, I would keep up on the water changes to keep those levels as low as possible. There is also a product called Prime. It detoxifies ammonia and nitrites.
[ame=http://www.amazon.com/Seachem-433-Prime-500ml/dp/B00025694O/ref=sr_1_1?ie=UTF8&qid=1361771821&sr=8-1&keywords=prime+aquarium]Amazon.com: Seachem Prime 500ml: Pet Supplies[/ame]
I can't personally recommend this product since I have never used it, but there are mmembers on here who have and say it does work.