The movie is probably from the 90's or early 2000. The woman gets a disease that causes her skin to harden. In the beginning she is healthy, then finds out she has a disease en starts getting sicker and sicker. I remember a scene that a dog sits on het chest while she is sleeping and she starts screaming because it hurts and she can't push the dog away. And also a scene where she meets other people with the same disease who are further along so it scares here. The people with the disease start looking a bit like skeletons, especially in their face around their mouth.