Thank you for posting your query through Healthcare magic.
If you had sent a photograph it would have been more easy to make a diagnosis. From the description, I presume that he has a traumatic echymosis underneath the skin of the sole. This is a common phenomenon in some constitutions and the bloody exudation beneath the thick skin goes unnoticed usually. It does not hurt much and goes without being noticed.
It is nothing to be alarmed about and seldom gives any suffering. Let it be there without puncturing or trying to open the loose skin of the part of sole. The bloody exudate will get dried up and when it is completely dried, the superficial layer of skin at the site will get exfoliated and the layer of skin underneath will become automatically thicker.
His blood may be tested for bleeding time
clotting time etc. to rule out any bleeding disease.
If any other systemic disease is diagnosed with him get back to me for Homoeopathic constitutional treatment.
With Best Wishes, Dr C. J. Varghese, Homoeopath, email@example.com,