First off I am not a horse owner. I am trying to help a friend of mine with a persistant health problem of her horse. Please be patiant with me, as I know little about horses and have never seen her horse in person. Anyway the problem is a pain in the horse's neck. She has not ridden him in years because trying to do so results in pain for the horse to the point he will buck. In addition whenever he tries to trot or run it will bring on a fit of pain which causes him to lower his neck and limp. She has taken him to several vets and none of them can find anything wrong. They have tried all sorts of treatments, even including leeches. (I honestly don't know how leeches would help in the first place) But she is to the point of frustration and desperation. The previous owner of the horse insist that he never had any injuries or birth defects. Can anyone give a point in the right direction as to what could be wrong? Thank you in advance for any help.