If you look at someone suffering from fibromyalgia, you would probably not even know it. Most people with this condition look perfectly normal on the outside. On the inside is a whole different story. Their skin or muscles may feel like they are on fire, or just ache, as if they were bruised. Most can't sleep a full night and after a while, this all takes its toll.
Here is a video called Fibromyalgia 101, that really sheds some light on this condition: