I would recommend that you show this to your doctors
">primary care doctor the next chance that you get. There are a few different possibilities here and your doctor will be able to help you figure things out.
For example, one of the most common causes of a 'double nail' like this would be prior trauma to the nail bed (such as stubbing your toe). Sometimes, the double nail will grow out and resolve over time, where as other times the nail bed may be permanently damaged, resulting in a permanent double nail. In more severe cases, your primary care doctor may want you to see a podiatrist
(foot specialist) to see if any additional interventions would be needed.
Another possibility is that could represent an fungal infection of the nail. Fungal organisms can penetrate deep under the nail, where they can cause deformities of the nail as well as thickening of the nail and changes in color. If this does turn out to be a fungal infection of the nail, it will probably need a prescription oral anti fungal medication to help it clear up prescribed by your doctor.
Start by contacting your doctor's office to set up a visit!