What Causes Discomfort In Throat Below Adam S Apple?

When I woke up this morning, my trachea was very sore from the indentation underneath my adams apple to about the middle of my chest. It feels worse when I lie down. This happened one other time about 3 years ago and lasted an entire day (as it has this time), and was completely gone the next day. It is an aching feeling, not sharp. Any ideas? Thanks!