Do a 20 or 30% water change, add some carbon, ensure NH3 reads 0. Don't feed the tank anything for a couple days, or at most, drop in a couple of pellets for the fish and make sure they eat them.
The cloudiness is probably just a combo of bacterial bloom and new sand dust. Not a really terrible combination. Don't panic
It's not that bad.
Make sure you keep the tank stable and cloud free for a month before adding anything else.