Ketamine is an anesthetic commonly used for horses but is used also used for severe nerve pain such as fibromyalgia, CRPS, etc.
It is also used for status epilepticus.
It is powerful and has side effects such as hallucinations.
It works but only should be prescribed and administered by providers that know what they are doing. For CRPS, it is usually done IV in a clinical setting.

@wheelerma I had a neurologist tell me the ketamine treatments I was having for depression were causing my headaches. I responded, "Amazing that it can cause headaches before even taking it, doctor!" I got a new doctor. Sorry for the snark. I can understand doctors not being up on all of the medications out there - there are a lot. Still, ketamine has done wonders recently for a lot of people with chronic pain and depression and has been on the news. It's an old drug with new uses. Did they say they would look into it or did they just dismiss it?