IC is actually one of the few conditions that DMSO is prescribed. I suggest you look into purchasing some high quality DMSO(glass container, 99% pure etc.) and apply it to the region, diluted with pure water of course and see if that doesn't help. Without having a catheter put in, I am not entirely sure of how much help it will give. You could also try a enema with diluted DMSO(I wouldn't use much though), and only after you have cleaned the rectum thoroughly beforehand.