I don't know about Parkinson's. I was at first thinking the health thing was a bit tin-foily, but she's been having a lot of incidents lately, now including fainting at a 9/11 service. Without knowing more facts, I think I'm hitching on to roo_ster's wagon: she's old.
That, in and of itself, doesn't necessarily mean much, but she seems to be showing that she's old and frail. Certainly the presidential campaign trail is rough - even for someone half her age. However, if she can't make it through the campaign without visible incidents, how is she going to make it through a much tougher four years as President?