Tuxedo Urchin White Spot/Fungus

[Kinnu]

Hey all,

Did water change two days ago. The urchin has moved around a bit since then but today I noticed a change on it. Ive attached two photos to this post if someone experience could look at it. Before the water change, the urchin was climbing in the corner up the tank, never went fully out. Im currently working and will do a reading test of the water tonight, but pre water change here are some numbers:

I know my Calcium and Magnesium were high which is why I did the water change. Currently, I only have inverts(Blue hermits, Cerith/Nerite Snail, 3 Emerald Crabs, One Urchin(This one), and a single coral).

Any idea what I did that might have hurt my little bud here? Currently alive and hoping it stays that way.

Hermits are active and lively. Emeralds and snails are active and lively at night.

 

[Kinnu]

Hopefully someone has some idea ^^

 

[Kinnu]

It seems as if the Urchin is losing it's spines at an alarming rate. I believe this means that it is passing. The single coral I have is also looking bad. I may have caused to much stress when changing water I guess. This sucks.

 

[Kinnu]

The Urchin is now bare and a hole appeared at the top. It is for sure dead sadly, to me at least.