Natural Remedies for Foot Corns

My husband has had a bad corn on bottom of his foot just under the pinky toe. He used a mixture of ACV, banatrol and aspirin on gauze wrapped over night for a few nights. He pulled out a tooth looking thing and now has a hole in his foot where it was with a pinpoint hole in the center of it. There are remnants of black specs that came out when the affected area was squeezed. What are those black specs?