Hi,
A 10-15% water change every other day is not going to cut those readings down. The pet stores will tell you anything you want to hear to get to sell fish. Your ammonia needs to get under 1.0 for hardier species, while under .50 for not-as-tolerant species of fish. Nitrates need to stay BELOW 40 at all times as the absolute maximum. NitrItes need to be below 1.0. You need to do a 50% water change EVERY DAY to get those readings down. Ammo-Lock is not going to be good. It causes ammonia spikes.
Get Prime or Amquel+, these help to detoxify ammonia, nitrites, and nitrates, giving your fish a fighting chance.
I did the exact same thing as you when starting m y tank. Unfortunatly, 1 week is not going to cycle a tank, espicially since you were adding no sourse of ammonia (i.e. fish food, pure ammonia). You need to read this to know what your tank is going thru. Best of luck, Brianna
www.fishlore.com/NitrogenCycle.htm