A bruise is an injury to underlying tissues or bone in which the skin is not broken. There are ruptured blood vessels which bleed into the tissues and cause discoloration. Bruises often result when soft tissue is struck hard, as in a fall or blow. Bruises are usually purple at first, then gradually fade over several weeks to various shades of brown, yellow, and green. A medical word for bruise is hematoma.
Most bruises require no special treatment.
Rest the injured part, particularly if it causes pain. Apply a cold wet cloth or ice pack. Keep a package of frozen vegetables in your freezer. It will conform to the injured area, is inexpensive, and is reusable. Wrap the cold pack in a cloth to protect the skin from too much cold.