Anemone are mostly water. They do not required any where near as much food as most people think from their fully inflated size. You anemone should be feed with food less than 1/2 of an pencil eraser.
When they are not well, don't feed them at all. IMO, if they are infected, undigested food will give bacterial much more fuel to multiply. That is why sick anemone should not be feed.
They will do fine with just light for years. They just won't grow or will not grow as fast but will be fine with good light and no food.
Your pictures are not clear but it does not seem to be a tear to me.