I have had the same problem for over 20 years and Dr. Shen has not found the reason (nor did Dr. Fazio or Dr. Remzi -- redo was done by Dr. Fazio). I know that one part of the problem is severe muscle tightness. Hard to believe or to identify but I've found that if I have some other reason for burning (e.g. too much bile or yeast) I tighten my muscles (guarding) and this increases the problem. I use a lot of lidocaine -- in particular lidocaine/steroid ointment helps but stretching the muscles and pelvic floor PT helps too. I'll try the vapo-rub -- never occurred to me.