The most common causes are bacterial or fungal infections which enters the skin around the nail that has been damaged by trauma, such as nail biting, finger sucking, dishwashing, or chemical irritants.
The yellow-green color
, indicates that a collection of pus has formed under the skin (called an abscess). If this is the case it may require an incision and drainage.
Warm soaks in a mixture of 50% warm water and 50% liquid antibacterial soap 3-4 times daily for about 15 minutes.