If you look at her Twitter feed, it's strongly implied she was diagnosed with some form of bone cancer in October. She tweeted then that she got some extremely bad news. Then, she had to have some form of surgery on the bones in her left leg in November. It was a big enough surgery that she was not able to walk for a while after -- though I imagine that's not all that uncommon if you've had surgery on your leg. That explains why people in the comments are saying "thank god she's alive." I don't know if it was cancer, but, if it wasn't it was something very serious on par with cancer.