If you are very ill, most zappers will be incofortable to use for you (the ultimate zapper is good but it's not practical to use...)
You should try a Terminator 2. You can wear it anytime, anywhere, below your belt. And there are others things in it that relieve pain. (orgonite and gems) Strange i know but it works well.
Be sure to improve your living habits and diet as well, zapper are good to accelerate recovery but they are not magic !