starfish worries

Question
Hi, my red sea star began to shed or give off a whitish, brownish mucus or skin like material off it's legs (a little below the middle), a friend of mine said it might be a mantis or something, because now it began to open a whole on the middle of it's back and you can now see through him, the whole is about 1 cm long or less, ever since the whole showed up you can't see his mouth.
I recently did a water change on saturday, may 17.
i have a yellow tang, two firefish gobies, 1 ocellaris clown (female), a green chromis, a reef haitian anemone, 6 reef hermits, two turbo snails, 2 trochus snails, a abalone snail, and the red sea star.
i had a fish die monday, ocellaris clown (male).
and have been closley watching my tank.
my salinity went up from 1.023 to 1.025 after the water change.
Do you have any idea what is happening?
if you need the information on testing  and/or tank specs let me know.

Answer
Hi Colin

I believe salinity bouncing may cause this. A few years ago i had a purple star, and my salinity bounced up a bit and he had a hole in his head, the same as you are describing. The best thing to do would be to keep him in clean water, and try the medicines melafix and pimafix, theyre liquid and natural. they mix together and are good at healing many diseases on saltwater and freshwater creatures, and they heal physical wounds. if you could quarantine the star, that would be good too. any other follow up questions feel free to ask