Really bad vulva pain. only after sex?

Can be multifactoria: It can be multi-factorial but could be a sign of vaginal and vulvar dryness ie due to lack of estrogen or a sign of interstitial cystitis or pelvic pain syndrome. Although generally it is a benign condition but you should see your gynecologist first to rule out any significant vagino-vulvar conditions. If gynecological evaluation is normal, you may then need to see a urologist.