The pain at the edge of the nail of the big toe may be due to the following reasons: 1. It may be a gray nail, which is a fungal infection of the nail and nail bed, causing damage to the nail and nail bed and local pain. 2. It may be nail fungus, which is also the most common disease, when bacteria infect the nail, local inflammation, it may be located at the edge of the nail, which will be swollen, red, swollen, hot and painful is more obvious. 3. It may It is fingertip infection, bacterial infection of the fingertip, localized redness, swelling, heat and pain. Further it may be some other causes, like injury to the nerve, or a herniated disc, which compresses the nerve and causes radioactive pain. There may also be osteophytes, or dermatomyositis or fasciitis, which can also cause pain.