Pain and Pain Relief
There are many conditions and illnesses that cause pain. They range from the relatively trivial such as a pulled muscle to the very serious such as cancer. On the whole most of the minor causes of pain will fix themselves over the course of a few days to a few weeks.
Generally doctors divide pain into acute and chronic. Acute pain is usually regarded as lasting for less than eight weeks. Chronic pain is pain that lasts for more than eight weeks. It's a bit of an artificial divide but is quite helpful clinically.
Of course what to a doctor is a minor problem feels very different to patient. Doctors can tend to talk about any non life threatening condition as minor, even though the pain and discomfort may be considerable.
There is often much you can do yourself to reduce pain and speed recovery. It depends on the reason for the pain, the symptoms and treatment available.