It'll probably pass. If you could have injured your chest area for any reason at all, you may have bruised a rib. That happened to me when I got in a car accident. I felt similar, like heavy breathing just felt [i/]different[/i] than it usually did. It passed. If you drink a lot of caffeine, that may be it too. That happened to my brother. He literally got "addicted", and had heart palpitations and belabored breathing. Trying to get off cold turkey just gave him a headache though. If you think that might be it, don't go cold turkey unless you want to take an ibuprofen every 12 hours.
If you start getting serious breathing problems, go see a doctor.