The pain inside the vagina may be due to a disease: 1. Vaginitis may be a disease that causes vaginal pain. 2. It may be caused by other diseases such as cervicitis, pelvic inflammatory disease, or tumor disease. When bacteria or virus invade the body, it will cause the vaginal epithelium to shed and the vaginal mucosa to become engorged with blood, which will cause vaginal pain. 3, it may also be caused by vaginal pain during intercourse due to excessive force of sex. This is not a disease, but a normal physiological symptom.