Gosh, loopylou, I am sorry to hear that. Maybe you need to talk to your doctor or find some ways that might help you minimise your stress. Meditation? Yoga? Exercise? Medication?
I read somewhere stress will make it happen and then a friend of a friend had it happen (she was going through a divorce). Since then I have worried that it will happen to me too, because in the last 12 months I have had all sorts of worries (not just PhD, but that was a big part of it).
Hope you get better soon, loopylou.