White bump on labia majora with puss, raised went down after hot water applied?

Vulvar abcess: You almost certainly had a gland become infected, associated with collection of pus, which usually resolves with drainage (spontaneous or with help) or resorption (with aid of heat in your case). Most of these are blocked skin glands that produce oil (sebaceous). Occasionally specialized glands of the vulva can become similarly infected, like bartholin's glands, and require medical attention.