Hi and welcome to HCM Since you must have hit your finger with a lot of force, there is a chance hat the bone may be injured. In any case some amount of pain and swelling of the skin and the tissues below it is normal. There would have been mild bleeding and swelling below the skin, causing the bump. The skin there is loose and can easily swell up. This will go down slowly. If there was some injury to the bone or tendons in the area it is possible that it has left a lump on healing which may be harder and take longer to heal. I would advise you to see an orthopaedician to rule out any internal injury, especially if you have severe pain or difficulty moving. If left unchecked the injury can form a permanent swelling or deformity. They will advise you regarding the necessary compression or treatment that you will need. Since there is no significant skin injury or bruising, there is nothing active to be done in that regard. Hope this helps. Do see an orthopedician.