@izzythepush,
I am basing my health claim purely on the video from her 9/11 appearance. Stress is the cause of so many factors and I think she is under an enormous amount of stress because of her desire that this her last and only chance to become president.
Trump may be older, but he is also a sociopath who, I believe, got into this race simply as a publicity stunt. He now tastes power, but I do not think the same stress plagues him because his ego is so grandiose that he cannot see anything but himself. Even if he was diagnosed with cancer, I think he wouldn't even believe it. I think he would believe that he can transcend anything.
I just have seen Hillary recently seeming more frail and, frankly it's sad, because I think she is the most qualified (by far) but stress and anxiety can do terrible things to one's body, and I think that the fear that Trump might win really weighs on her, as it should on all the American people.
I think she cares about this nation and if there ever came a time where she truly believed that she physically could not contest the mongrel that is Trump, then I think she would step down and let someone else contest him.