There is often a delay between the stressor(s) and an outbreak. In your case it's probably the cummulative effect of the move and the following ammonia spike. With the ammonia spike being the biggest stressor. The nitrite isn't as big of a concern since it is not very toxic in saltwater.

If it were me I would go get some instant bacteria culture (biospira or tlc are good ones, TLC is much cheaper though) to beef up your bacteria population. Then start feeding very frequently (like 10+ small feedings per day) with a variety of quality foods.