It sounds to me like your live rock was not fully cured when you put it in to your new aquarium...
What potentially happened was that after placing the live rock in, initially the ammonia went up slightly, but the bacteria already in your tank quickly began converting that to nitrite, and you are in the middle of a mini-cycle.
If that IS what happened, the bacteria already have your ammonia well under control, and this means your nitrite should slowly decrease until it is gone over the next few days! Let us know!
38 Gallon (Freshwater): 1 Green Swordtail, 3 Yo-Yo Loaches, 1 Clown Pleco, 1 Blue Gourami, 4 Otocinclus, 7 Cherry Barbs.
46 Gallon (Saltwater): 60 pounds Lalo Live Rock, 60 pounds aragonite sand, 1 Coral Beauty Angelfish, 1 Peppermint Shrimp, 1 Mushroom Coral, 1 Emerald Crab, various snails and hermit crabs.
10 Gallon (Saltwater quarantine):