A confusing day seemed to down on Mystic Falls that day. How did Damon know that day was confusing?

Well, for starters, his younger sibling was stuck in bed, choking and coughing even though vampires don’t get sick. Well - Damon though that.

Worst part of that day was, Damon was willing to risk his health to get his younger sibling..? This wasn’t something he was used to - whatsoever.