Physical injury
Strong nails can be injured when a heavy object lands on them or when they get slammed into a door. Due to a large number of nerves under and around the nails, the injuries may result in excruciating pain. In some cases, a physical injury to the toenails or fingernails may result in bruising or make your nails fall off before they are replaced. Injured nails feel soft as they grow and heal.
Nail biting
People who bite their nails experience red and painful fingertips. In some cases, the Cuticles may also bleed. Also, biting your nails and the skin around them makes you more susceptible to certain infections. Symptoms of the infections usually disappear when you stop chewing your nails.