A black line on your nail (medically known as melanonychia) causes a streak of dark pigmentation that runs along the nail bed ...

When trauma occurs, blood may pool under the nail, creating a dark purple or black discoloration (medically known as a ...

Nails may hurt due to an infection, nail biting, injury, or other causes. Treatment depends on the cause and may involve home remedies and medical treatments. Nail pain may be due to temporary ...