Causes of vulval pain are due to all except:
Neuralgia of the genitofernoral nerve
Herpes
Vulval vestibulitis syndrome
Lichen sclerosus
Vulval pain syndrome
Vulvar pain sensation may be burning, stinging or irritation. It may be due to several reasons:

Aphthous ulcer
Vulval dermatoses
Herpes genitalis
Pudendal or genitofemoral nerve neuralgia
Vulvodynia (burning vulva syndrome)
Vulval vestibulitis syndrome
Referred pain from urethral or vagina
Psychological