Just out of curiosity, could you PM me the name of the breeder you got them from? I had a similar problem earlier in the year with 3 White's that I got from a certain breeder at one of the Doncaster shows. One passed away within 48 hours of having it, the other one the next week, and the third one a few weeks later with similar symptoms to what yours had.

I don't know how long you've had them, so it might not even be relevant, but if you've only had them a short time it very well could be.

So sorry for your loss, I know how hard it is to lose a beloved pet