So sorry for your loss! Could the cloudiness and odor be from some type of bacterial bloom? That may have just been a result of what was already happening before it.
Maybe something introduced in the LFS water aside from the phosphates was slowly reproducing and the aggressive water changes gave it some kind of boost that let it grow rapidly and suffocate the tank.
I once added some countertop distiller water for a top off when I didn’t have any RO and within a day my display tank became so cloudy I couldn’t see in. Massive bacterial bloom. Before it got that bad I saw that one of the clownfish looked like it was breathing fast. I searched and read a bloom could consume all the oxygen and suffocate the tank. That would also drop the alk and pH as a result.
I did a partial water change, put a bubbler in the display and a UV light in a sump chamber, and prepared for the worst. It took a week to clear up enough to see in. The livestock survived. The macro algae in the tank did not.
Here’s what it looked like 9 days in: