What Causes Swollen & Painful Vagina Post Sex?

I've been having painful sex for...months. It's sensitive and swollen to the touch directly on the inside top right side....one of the two symmetrical...things that I don't know what they're called. They're like bumps, but one is swollen and bigger and hurting. It's been a long time. I tried to get help, but I really think my doctor didn't know what she was talking about. Also...is it possible to tear the thiner, smaller lips right outside of the vaginal opening? I'm just a painful wreck and I need help.