The most important thing is usually to re-estrogenize the vagina—with localized, not systemic estrogen. I haven’t seen a single oncologist not agree to allow breast cancer patients to use this. There are a couple of really low-dose estrogen products to use in the vagina; the estrogen is not absorbed outside of that area. Vulvodynia occasionally benefits from the localized estrogen too, or there are some topical options.
A thorough and detailed pelvic exam could help to determine where the pain is arising (vulva, introitus, vagina, pelvic floor muscles, and/or vaginal cuff). Each of these has a different solution, or maybe a combination of options.
A lubricant will help somewhat with sex, but a moisturizer (like Yes) is more important for prevention and long-term preservation (vaginal estrogen can accomplish this, too). Some of my patients use a topical anesthetic in the area. If you have lost some caliber of the vagina—some narrowing, dilators can help restore that. Some women with longstanding pain with intercourse develop vaginismus, in which the involuntary muscles of the vagina go into spasm.
Don’t stop trying! Usually we can restore comfort!