Hey ljtan55, did you wash the filter/s out with cold tap water or warm tank water? If you used cold it would've killed the beneficial bacteria and your fish could be exhibiting nitrite poisoning, I've seen a couple of my discus do this once when the filter wasn't properly cycled. It's your filters that cycle, not the tank, so major water changes doesn't affect the bacteria, there is little or none in the water body itself. With undergravel filters the good bacteria is in the gravel as opposed to a filter sponge.
Did you vacuum the gravel? Maybe this disturbed detritus from the bottom and has made it cloudy, is it white or green cloudy? If you haven't already would be a good idea to clean out the filters to help remove it. HTH