Not to worry.. for detailed information do direct online consultation

Hi. This could be due to melanocytic nevi. As such Nothing to worry about .

A narrow black line that has formed vertically underneath your nail is called a splinter hemorrhage. It occurs for a variety of reasons and may be harmless. The condition is caused by damaged small blood vessels underneath your nail. Characteristics include the following: It’s black or reddish brown in color and It doesn’t change appearance when you apply pressure to the nail. Contact your Dermatologist if you’re sure a black line on your nail wasn’t caused by trauma. If the trauma has caused another condition or doesn’t seem to be healing on its own after several weeks, you should see a doctor.