what happened to my damsel?

[lucano]

Hello, I'm a beginner and my tank has been running for 2 months now. Last week I did a 50% water change because before i used tap water and last week i starter with ro water.
After that i did a couple of salinity jumps (went from 1.025 to 1.020 and then back up to 1.025). My values seem good: ammonia 0, nitrite 0, ph 8 and nitrate 10.
But yesterday my damsel has developed these white things (see pictures). Moreover my arrow crab lost 1 leg and 1 pincher. And my leather coral is not opening up anymore. I also have a very aggressive cleaner shrimp that seems picking on everything and everybody.
Can somebody give me some suggestions on what to do? thanks in advance.

 

[dbl]

I'm not a disease guy, but I did move this thread to the disease section where the experts hang out.

 

[Big G]

White, cottony, fibrous, or cauliflower looking growths usually are lymphocystis. It's a usually harmless viral infection. Pristine water quality, high quality foods + vitamins ( I prefer Beta Glucan), and a low stress environment will help deal with this condition.

 

[lucano]

White, cottony, fibrous, or cauliflower looking growths usually are lymphocystis. It's a usually harmless viral infection. Pristine water quality, high quality foods + vitamins ( I prefer Beta Glucan), and a low stress environment will help deal with this condition.

thanks