The FDA is becoming more strict about all controlled substances, especially about "off-label" prescribing, that is, prescribing it for a condition other than those it has been specifically approved to treat. As a matter of fact, many doctors are becoming nervous about prescribing ANYTHING off-label, controlled or not!
For example, I'm allergic to a common asthma medicine. So I asked my doctor about using another medicine, also approved for asthma, in a slightly different way than it is usually prescribed, since several studies found it works well that way. He basically said, "I'll give you the drug, do what you want, but I don't want to know, because I could get sued for prescribing off-label."
Speaking as someone who was diagnosed with fibromyalgia eight years before any drugs were FDA approved to treat it, I find this obsession with sticking to the labels pretty funny. Heck, I'm not switching to Lyrica or Savella! They cost a fortune and I don't like the side effect profiles. My tricyclic, nortriptyline, costs about $12 per month and works fine. Of course, no drug company will bother getting that approved for fibro. It's generic, they wouldn't make any money on the deal.