Some diseases can cause rapid weight loss; some kinds of cancer, for instance, or gastric conditions.
I commented weeks ago that HRC had lost weight, but I also thought it was maybe a reduction in use of steroids for whatever ailed her, during the campaign. She was so huge then that she was incapable of walking, and a stair step or two proved a disaster for her on way too many photographed occasions, notably in India and other places.
Re: cough - congestive heart failure and GERD can cause coughing.