I seriously doubt it is ich because no new fish have been added to the tank in the last 2 weeks, or have they?
Ichthyopthirius can only get into a tank from a contaminated fish, plants or water from an infected tank. If you have not added anything new in the last 2 weeks it will not be ich (whitespot). Also if it was ich, the other fish would be showing white dots by now. It spreads very quickly and the white spots actually drop off the fish after a few days. When the white spot cysts drop off the fish they settle to the bottom and the protozoan inside the cyst multiplies for a few days before the cyst ruptures open and hundreds of new white spot parasites get into the water and infect the fish. Basically the fish get a few white spots, the spots disappear for a couple of days. Then the fish get covered in white spots, then a week later the fish are dead.
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DO NOT pull the main tank apart and wash everything down. You will damage the beneficial filter bacteria and the tank will go through another filter cycling process. If you want to wash ornaments then take them out and wash them with fresh water, that is fine. If you want to clean the tank and gravel then wipe the inside of the glass down with a clean fish only sponge, do a complete gravel clean, and a 75% water change each day for a week. Then wash the filter media out in a bucket of tank water. That will clean the tank conditions up and you can leave the fish in there while you do it, and not have to worry about wiping out the filter bacteria.
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Do not use medications unless you know what the actual problem is because they can cause problems to fish and filters