Oh, honey! I'm so sorry. . .
I wish I had seen this thread yesterday, but she went so fast, there probably wasn't anything you could have done to help her. . . still
sorry you had to face it alone.
If she was in a community with other fish, I would recommend doing a water change, and keep a close eye on the others for any signs of the same issue with them. Hopefully this was a random one-time thing, but if not, we have an area of the forum dedicated to helping with illness
. If you see ANY signs of this 'white spot' on your other fish, please fill in the Diagnosis form you will find there, and post for help.
*hugs* I'm sad for your loss. . .