She’s not healthy enough to give speeches and prepare for the remaining debates. And by “prepare” I mean memorizing scripted answers to the questions she has already been provided with by the “moderators”.
https://www.youtube.com/watch?v=582fpY_Xmwc&feature=share
Dr. Ted Noel explains how Parkinson’s sufferers on Levodopa, the medication, take what’s called “drug holiday” - periods of time off the medication because it’s effectiveness is waining. By going off for a while, and then restarting, the levodopa will become effective again and enable her to endure a 2-3 hour debate without any extremely obvious events.
This would explain why she disappears from the public for periods of time.
He examined the debate video, and did find that there were symptoms of Parkinson’s going on with her that most of us missed.