Answer:
Toenail fungus. Nail fungus, or onychomycosis, is a common condition. ...
Ingrown toenail. Ingrown toenails are one of the most common and most painful toenail problems. ...
Toenail trauma. ...
Clubbed nails. ...
Discoloration of the nail plates. ...
Nail-patella syndrome. ...
Leukonychia.