What Causes Black Finger Nail With Swelling Around It?

Hai, I m Albin (26).I have a black finger nail which have yellow color dust underneath and on top back end too. I noticed it 12 year back. Only now it starts pain.Top of the nail is very rough. Nail is Slightly bigger than other hand.Skin around it just like swelled but I think it s not. Since it have no pain before Dr s just avoided it(no medicine).What exactly is this disease? Is their a cure for coloration and pain?