Use Comfrey root on the finger. My local healthfood store has it, your likely will. Make a tea, and put the grounds on the finger, and seal it to keep it wet. Cover the entire tip, and leave it for a day. It will do wonders. It can be bought in a tincture, but that might hurt through the hole in the nail. One day heals most bruises, then the nail will need to be kept clean as it grows out.