Pink Eye Cures Treat

why does my pink kissing gourami from one day to another ended up with like pimples all over its body and eyes?
i bought it a week ago and just last night i saw it has those pimples or whatever they are all around its body. i have changed the water just to make sure but i dont know what it could have caused it. what is it and how can it be treated or cured?
Lets dispell one myth, Gouramis get signicantly darker when spawning- they dont red red sores or acne!Gouramis do get Acne, according to All Experts answer column. It’s one of a few times I’ve heard of it, but they apparentty have seen more cases and they trat it with Melafix (ich and velevet will not respond). Just to be safe, I would also add an anti ich/velvet medication. Most people have seen ich but velet is smaller, darker and peppery. In either case Coppersafe will kill it in day, standatd Ich Medications like Quick Cure and may take a few days longer. Malachite green preparations don’t kill velvet as well. You can raise your tank remperature to 80 (but is should be close to that anyway) and add kosher salt only (not table salt) at the dose of 1 teaspoon per 3 gallons. but this will only help, it very seldom works without an ich/velevet medication. It may help gourami acne well, but this is newly described condition, and hopefully isn’t related to Dwarf Gourami Iridovirus which cases red sores, but so far, has only been seen in Dwarf Gouramis.