Moving Crown

I bit down hard on some popcorn, and a piece of it went under my gum around tooth #5, which has a crown. The crown was placed 12 years ago, and it had root canal treatment with a short post.

A few days after the incident, I visited a dentist because I felt some discomfort and pain when using a water pick near the area. An X-ray showed no visible damage to the crowned tooth, and I was told to give the gum time to heal. However, the crown has since started to feel loose.

I have an upcoming appointment to see the dentist, but I want to be prepared. What could have caused the crown to loosen, and is there a chance it can be re-cemented, or will I need a new one?