I'm sorry to say, if the whole plant looks like this suddenly, that looks like trouble from the root, such as phytopthera infection. Check the trunk of the plant, all the way down, and particularly near the base or the graft - you're looking for soft spots, anything that's cracked or weeping, anything that shouldn't be there.

If the trouble is at root level, there may be nothing obvious for you to find, but there's nothing that can be done to save it if there is trouble with the rootstock or graft.