you need to see your doctor about this.
Is it only on the left side? Does it seem to travel to your back as well? Do you drink excessive amounts of alcohol? If you answered no, yes, and yes, it could be pancreatitis, or inflammation of the...
It might be. Actually there are lots of disease you can get from smoking.
There is a chance that you may have broken some of your ribs. If you are really worried/concerned you have got to see a doctor ASAP.
Indigestion.