For such an issue, I would probably use DMSO - BUT - the ONLY reason I would do DMSO would be because I would probably NOT do "auto-urine therapy". Which is, I suspect, what is actually called with regard to interstitial cystitis. Fresh urine. It tastes like mineral water, it's filtered plasma and sterile with living stem cells which I happen to think is key to its efficacy with regard to any illness and I've read that they don't live long once evacuated. Something like around 20 seconds so you want to take them back before that.
For some reason, men don't seem to have as much of a problem with urine therapy as women so it's what I'd do if I was a man.
BUT, I'm not a man so if I didn't have DMSO or couldn't get some relief after the very first day of a dropper of DMSO under the tongue morning, noon and night, I would probably switch to urine because the worst thing about being sick, for me, is the interruption of my life which is even worse than the idea of drinking urine if I can't get an indication of some sort of end to it. I just won't stand for it.