My crown including post has fallen out, advice?

Have had pain in this tooth for a couple of weeks previous and a swelling of the gum above the tooth for a couple of weeks, I'm hoping the dentist will see me tomorrow and be able to re fit the crown easily enough. The pain has subsided since the crown has fallen out..... I'm thinking maybe abscess? If this is the case will the dentist be able to re fit the crown or will the abscess complicate the matter?