I have been suffering from this ever since my J-Pouch "take down" 4 years ago. It has gotten progressively worse. It occurs whenever a.) I eat certain foods,i.e. tomato sauce, b.) exert myself physically (The level of physical activity that can be tolerated before the onset of burning has diminished with time) or c.) for no apparent reason. 

My muscles have almost completely atrophied resulting in a very significant change in lifestyle because the only relief is to sit down and do nothing until the burning eases.

Several gastroenterologist have told me they can think of nothing else to do to alleviate the burning. My pelvic floor therapist believes the anal sphincter and puborectalis muscles go into spasm and irritate the pudendal nerve, which nourishes those muscles, and this is what causes the pain. Pudendal nerve block injections have not been beneficial.

Does anyone know of someone with a similar problem who has found a treatment that provided some relief?