Look: The 3 things mentioned in this thread, restless leg, irritable bowel and fibromyalgia, all became widely known at the very same time as the drugs for those ailments were first advertised. The advertising itself created the markets for those drugs by convincing people that they had something wrong with them and it had a name and a treatment. Since these particular drugs have few side effects and counter indication for them is rare doctors freely prescribe them,off-label even.
I am certain that there are people that benefit greatly from both the diagnosis and treatment of these particular things. I am just as certain that a majority of the people taking drugs to treat these things are neither afflicted with them nor are they helped by the treatments beyond placebo affect.
If you are one of those unlucky enough to be genuinely affected by IBS, Restless Leg or Fibromyalgia I hope that your treatment is going well and I wish you the best.