Something wrong with sarasa goldfish

Thank you all so much for the help. Amaterasu looks better already! I'll continue to treat her until the end of the 5 days like it says. Hopefully that will do it and she'll be a happy healthy fish for a very long time.
 
I have another quick question which doesnt relate to amaterasu, but instead another fish. (though i will say Amaterasu looks much better, seems to be happier. it's been the recomended 5 days using the Maracyn-TC, however she does still seem to have a white spot or two just beneath the surface of her skin. should I continue the treatment or just continue with the 10 days for the medicated food?)

My question is: can Maracyn be put into a tank that has been medicated with Melafix without changing the water? I was treating my fish, Inferno, for fin rot and now he seems to have some fuzzy patches that look like all the pictures i have seen of Columnaris, which I think might be because I stressed him out doing a large water change on his tank. I dont want to change his water and stress him more, so is it okay to put maracyn in the water, even though its been treated with the melafix?
 
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