I have been experiencing the same thing. I have tried everything from messages to chorpractic ajustments. Ya,it feels good for a short time then, the next day it is back to the same ole pain. I recently went to my DR. and explained everything to him, he says that this is caused from extreme stress,anxiety, and tention. I told him that I had that for years and never had a problem before. He said that due to ongoing stress that eventually the nerves and tention strings would wear out and start short circuiting,(kinda like bare wires). He gave me some muscle relaxers and it really helped me. By the way you are explaining the movement of pain from the shoulders into the neck and upward to the back of the skull, this exactly where it affects me. I would bet that your wife is constantly under extreme pressure,stressful, with anxiety. Does this describe her? I think if she could get away and relax some with no phones,no pagers,no children to take care of,no deadlines,and no one to be bothering her, she could take the muscle relaxer and would feel much better. I think that the muscle relaxer just takes the edge off because the stress facters are still there. Try what I suggested and see if I'm right. It certainly couldn't hurt, and oh by the way,I don't think falling off the horse has anything to do with it. Just coincidental. Going to the neur. Dr. is a good thing. At least this will finish the diagnostics...Sometimes just getting away from all the everyday stress and activities can do wonders.
I don't have much to offer except that I believe it did have something to do with falling off the horse. The fact she gets tingling in her hands and feet suggests that something is going on with her spine. Did you have a CT scan with the fluoroscopy?
CT scan -"invaluable in diagnosing and treating spinal problems and injuries to the hands, feet and other skeletal structures because it can clearly show even very small bones as well as surrounding tissues such as muscle and blood vessels."
(www.radiologyinfo.org/en/info.cfm?pg=bodyct&bhcp=1)
If you have already had this test and nothing showed I would keep getting further opinions until I received the treatment and answer I need.
How did she land? Was it on her bottom? I've heard of motor bike riders sustaining injuries from landing down hard on their rear end. The injury is very hard to find unless specifically looking for it. What happens is the spine is forced upwards towards their skull from the impact to the base of their spine. I hope your wife finds relief soon. Good Luck.