Most of the fish we keep come from murky ponds, lakes, streams and rivers. The clarity of the water is for our pleasure not their's. They could care less IMO. Patience is key as others have already said. Finesse the tank when working on it. Too much fiddling can cause more issues. After all of this you could try a simple UV filter and see if that helps.
I know this is driving you crazy. Trust me I have been there before. When I encountered this same issues years ago when I was less experienced I was doing more or less what you have already done and ended up with the same results you are getting, nowhere. These days when this happens, I just leave the tank as is besides normal maintenance and wait a week or two and the issue usually resolves its self. If not, I start taking action but doing so gently while leaving time to see if what I did actually helped or not.