I've had a similar problem before, but now, because of this, I no longer care for adult spadefoot toads, just raise babies...

I kept mine with a few other species for weeks, and she was happy, large, fat, and healthy. One day she hadn't dried up or regurgitated her insides(ew!), but had burst.

I'm glad to hear I'm not the only one, but I have no idea what happened! ): Sorry!