Did you ever find an answer? Really could use the help
Did you ask a gynecologist or just your primary care doctor? Sometimes, the GYN can tell you more as this is their area of expertise.
I really don't know what would cause the burning. Have you had any yeast infections or bacterial infections ? How old are you, are you near menopause? Does it happen more near your period? Are you extra dry in that area? All of these things can cause burning and itching as well. Are you a diabetic? This is common in diabetics. Are you on any meds, some of these can cause your problem too.
I wish I could be of more help, but, if you answer "Yes" to any of my questions, then that could be your answer. As I said in the beginning of this post, if you have not already done so, see a good GYN, they should be able to help you.