Labial soreness may be caused by local inflammation, more commonly known as vaginitis. It is best to go to the hospital for a routine leucorrhoea examination to clarify which pathogenic bacteria are present, and then target the treatment. The most common treatment for vaginitis is localized suppositories, which can reach the lesion and reduce inflammation, and oral medication. It is also important to keep your perineum hygienic, avoid tight underwear, and bathe and change your underwear regularly, preferably in hot water.