It is normal to have some pain and swelling following an injury.
Pain, redness, and swelling can occur with inflammation (such as with bursitis, arthritis, or tendinitis).
Pain and swelling that occurs with other symptoms may be caused by an infection. Symptoms may include:
Infections can occur without a known injury to the affected area. Most infections develop when germs (bacteria) enter the cut, punctured, or scraped skin after an injury.
Prompt medical treatment of an infection can prevent serious complications.
WebMD Medical Reference from Healthwise