My boyfriend spanked me during sex and what do I do for the pain?

My boyfriend and I enjoy erotic spanking during sex, but last night, he got a little carried away with it. He spanked me hard and very frequently. My butt now has red streaks on it, feels very sore, and it hurts very badly to sit down. What do I do about the pain and how long will the redness take to go away? I thought about putting vaseline or lotion on my butt.

Serious answers only please.