A week ago i was catching a ball and my finger bent back. it's still very sore and a bit bruised a week later. what's wrong with it?

Contusion/bruise: A bruise, or contusion, is caused when blood vessels are damaged or broken as the result of an injury like yours or a blow to the skin. The fingers have a small confined space, especially around the knuckle/joint areas, that will take more time to heal than other body parts, and especially with the constant use of our hands/fingers-healing naturally takes longer.