How are your other two acting?
I know when I got my platys I was concerned about some sort of internal parasite becuase they had whitish to clear poop but after they destressed and started getting used to the new digs they are acting healthy and normal. IMO
they seem to have a little more noticable reactions to stress than my other fish.
I have a wife, a toddler, a truck, a planted tank, a reef, a snake, 2 Bearded Dragons, 5 Milk Frogs, and 2 dogs.