Three Days in Grief
First, read this verse: After three days they found him in the temple... (Luke 2:46a)
Did you ever notice that they search for Jesus in Jerusalem for THREE DAYS? I don't ever remember paying attention to that before. Imagine searching for your child for three days. When my boys were small, if I turned around and they weren't where I expected them to be, even for a moment, my stomach dropped. I can't imagine searching for three days.
According to Hamilton, the word Luke uses in verse 48 that is translated as "great anxiety" is the Greek word odunao. This word is used again in the book of Luke as part of the story of the Rich Man and Lazarus (Luke 16:19-30) to mean the torments of hell. I think we can understand why Luke would use that word - why Mary might use that word to describe their state of mind during those three days.
Three days in terrible, wrenching grief. Three days of not knowing where their child was - not knowing if he were dead or alive. It won't be the last time Mary has this experience.