I wish I could give you some information on Ketamine addiction and the likely course of things to happen when detoxing off of it, but I'm only vaguely familiar with it. The one thing I can tell you is that ketamine isnt physically addictive, however it does rank right up there with the likes of Cocaine as far as the severity of psychological addiction.
In addition to this there have been some studies done that point to certain effects on specific areas of the brain. These seem to be temporary and the recovery seem to be at least partially dependent on replacing certain vitamins and nutrients that are leached out of the body and brain by prolonged ketamin use.
Other then this very basic information, and the suggestion of speaking with a physician about helping with some of the psychological addictive aspects, as well as what the possible relationship may be to the stomach problems your having, the only other thing I can suggest is maybe finding some NA meetings in the area, at least at the beginning for some support and people with possible first hand experience with ketamine addiction.
Hope that helps at least a little bit....