Really cloudy water

[Pan]

nyone know what would cause my water to go extremely cloudy? I had a fish die, rainford goby...i took him out when i found him. Tested ammonia, test revealed a little, like .25 or so...the lowest i can read thats not 0. did 10 gallon water change (20 gallon tank) everything looked okay then abmmo 6 hours later water looked like water that had milk poured into it. Damn i can wait to get the bigger tank.