Even finding doctors that will give you injectable/IV ascorbate is not easy. The following will give you some information about the injectable solution: http://www.orthomed.com/civprep.htm
If you start very gradually ingesting an amount of ascorbic acid that you can handle comfortably, even if just a few hundred milligrams, I believe that you will find that you can gradually comfortably handle more and more, as your overall health and internal cleanliness improves.