hello i have read your query.it can be a planter wart.Plantar warts are the warts that occur on the soles of the feet. These types of warts may resemble calluses or corns, but you can tell the difference because plantar warts disrupt the natural lines of the skin and may have small black dots on their surface, which are tiny blood clots in blood vessels.treatments available are freezing of warts to destroy the virus.Persistent or very painful plantar warts may need to be surgically removed.its better you consult a pediatric dermatologist. hope this ans helps.take care Regards Dr. shesh