Corns are mainly caused by frictional irritation or local extrusion resulting in abnormal skin keratinization and formation of keratin plugs. If you have keratotic papules or patches on your feet that are raised on the skin and resemble corns, you can go to the hospital for a dermoscopy and consider plantar warts that are caused by human papilloma virus infection. The actual black spots are the result of broken capillaries and bleeding. The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. If the effect is not obvious, you can also inject BCG polysaccharide nucleic acid intramuscularly to regulate immunity.