HELP!! What happened to my Blue spot???

[Whatigot]

Looking at your location, I would guess it was the nearest of the LFS to you that you purchased it from?
I shop there frequently and am always very careful when selecting livestock.

There is a small possibility that you have terrible luck and these 2 fish were either at the end of their life cycles or underwent significant stress before you gave them a good home....

I hate these reef mysteries and it's rough to lose such cool fish and not know why even aside fromt he monetary cost.

Good luck on putting this puzzle together.