I haven't had that one myself, but that's actually considered one of the classic symptoms of chronic non-bacterial prostatitis. That condition is pretty much synonymous with Chronic Pelvic Pain. I was diagnosed with prostatitis, although my symptoms are more just burning in the tip of my penis and in the rectal area. I did have an area of pressure around my tailbone at one point, although that went away once I focused on relaxing my pelvic floor.
I'm pretty new to Sarno's work (just bought his book less than 24 hours ago), so not sure if that particular symptom is something people have had success with using his technique. I know some folks taking another mind-body approach (the Wise-Anderson method) have focused on relaxation, with the theory that many tense their pelvic floor in response to stress and relaxation can solve that. I haven't done that method myself (the guy who developed it charges several thousands of dollars for a workshop in California), but I think there might be something there. I'm curious also if anyone has applies Sarno's methods to that same symptom and has success.