Whiplash declining, is this the same fate for fibromyalgia ?

I can recall from my 35 years of  medical practice that during  the 1970-90's period whiplash was a common complaint of many patients after rear end vehicle collisions. Many came walking into the office with neck braces. The standard joke was that there was often a race between the police and legal profession as to who who got to the collision site first.
During this period I also worked for a time at the workers Compensation Board and found many claims were diagnosed as whiplash. I seem to recall this diagnosis also became prevalent for children engaged in sport activities. When it seemed to reach epidemic proportions in some countries, employers finally began taking their compensation boards to courts. It seemed that after these court cases the incidence of whiplash ( cervical spine syndrome) began to decline even though I don't believe that  a casual relationship was proven.
To me it seems that fibromyalgia, also called chronic fatigue syndrome is beginning to show similar signs of decline. That should not be surprising because in my opinion this entity is basically a syndrome and not a disease.
 A syndrome is defined as a group of signs and symptoms just points to a particular disease.
 After reading a recent editorial in the Wpg Free Press where one doctor suggests that concussions may already be over diagnosed, I wonder whether concussions will take over from fibromyalgia.