If you were to spend a moment thinking about a time when you were unfortunate to have an accident i.e. a trip or fall, cut yourself while chopping vegetables, sprain a muscle, etc. what happens? You would probably feel an immediate pain which would then be followed by the longer lasting dull ache until it goes away.
Doctors will classify pain as Acute Pain which is caused by some form of injury to the body warning the brain of potential damage and requires action. It can develop slowly or quickly and last for just a few minutes or months and will subside as the injury heals.
Chronic Pain this is pain which will persist long after the trauma has healed, and sometimes can occur even in the absence of a trauma. This type of pain does not warn the body to respond and will usually last longer than six months.