About six years about a fine line appeared along the nail bed and the nail in that one area was weak. About a week ago it started throbbing real bad and the line became thick and red. Any ideas?
[Here's a pic.](http://imgur.com/AwS0yh1)
That is called a splinter hemorrhage. There are small blood vessels call capillaries that bring blood to the nail bed. Damage to the nail when you clip the nail, or if you are a biter, can cause this. It will eventually go away on its own. Under very rare circumstances, splinter hemorrhages can be a sign of congestive heart failure, but as long as you're not a 60 year old with previous heart attacks you don't need to worry.