Ok, you have a bruise. This is an area of trauma to the tissue (it's broken up) and you had bleeding under the skin (that's the black and blue.) So the area is sore and tender. You are pressing on this area, essentially pressing on damaged tissue. So if I were you, I'd give it a few days REST and STOP PLAYING because what will happen is the area will receive circulation and "clean up cells" that go in and clear out the damaged cells and start to rebuild the part that was squashed. In this case, the pain means "STOP FERGAWDSAKE." Icing the area (soak in some ice water) to reduce the swelling can help. Make sure you keep it clean because fingers get infected rather easily because we stick them into everything and bacteria are everywhere. (If the swelling gets redder and hot, go see someone. Fingers can get infected where you don't see on the surface and they can be a bit annoying to heal up. This is unlikely, but it could happen.) When working, keep the finger covered to protect it and to prevent more damage and to keep it clean. Not medical advice, this is just first aid.
