after sex question

Why after sex am I swollen? Not like in pain. I've been having sex for years and the man I am with now it longer and wider then I have previously encountered, not in a bad way. But these last few times I find that my clit is still very hard after we finish. (We are long distance so we do not have sex everyday) it's really the first time my clit has done anything, in general  I've never been much of a clit person always a internal orgasm-er so to speak so this is a little New for me. And I can't help but be concerned.