I have had pain in my vulva for a year and a half now due to injury. i have been to doctors. how do i tell if my pain is from virecose vains or nerves?

You can't: Early twenties female with pain post "injury" does not tell us the most useful info, i.e., the mechanism of injury, but she now has vulva pain. Pain is often referred from pain generator to site where it is subjectively experienced. Chronic vulva pain might reflect symphysis pubis joint injury or pain referred from an injured sacroiliac joint. An osteopath might be best specialist to sort out.