This sort of heat is experienced in different cases. For example, yeast infections, soaps, or laundry detergents can all cause it. It might also mean someone has an STI if they feel this kind of pain. For relief from the burn you might want to consider wearing loose-fitting cotton underwear that doesn't trap moisture and enables the skin to breathe, avoiding using scented products like pads or tampons which could further irritate already sensitive tissues during your period, also try washing with just water around the vulva than any soap. If you are still feeling the same, visit a gynecologist.