Couple of thoughts....
Is this what we're talking about?
My first thought was to google: ketamine treatment centers maryland headache
which is where I found the above link. Also found this:
If that search turns nothing up, you might contact doctors who are working with this in other nearby states (like the author of the above article), or doctors in Maryland using ketamine for other reasons, and ask them if they know of anyone doing what you're looking for.
Contact your insurance company. Even if the treatment/therapy is not covered, they may know of a doctor who is doing it.
I would also try asking this question on the Reflex Sympathetic Dystrophy (RSD and CRPS)