She implied in her interview that she had been ill longer than just the Friday...
"...only Steven and Helen knew how ill i was all that week, they kept checking i was ok and helping me out....." (OWTTE)
she then also said...
"...i am still not better, but i am better than i was...." (OWTTE)
Indicating that it was probably some sort of virus and that the task led her to being dehydrated. I think it was dehydration that she was in the hospital for.
(or words to that effect)