About 15 years ago I had some trauma to a finger, all recovered and just s small scar under the fingernail remains. A couple of days ago I noticed a mark has appeared on the nail, similar to a bruise. Can't think why as i didn't bang it against anything and it isn't sore. I would say it's slightly fading but is growing more towards the base of the nail in a kind of vertical pattern. I've attached a picture but made the mistake of googling so am I being unreasonable now thinking the worst 
...apologies for cheap photo, can't he a phone to focus on the bruise properly.