Aclient complains to the health care provider that he keeps getting hard skin on the sides of the great and little toes when he wears certain pairs of shoes.

This is probably caused by ill-fitting shoes putting pressure on certain areas of the foot and would be called a Corn.
In this context, corn refers to some sort of calluses that appear if we constantly use ill-fitting shoes. The pressure that caused by the ill-fitting shoes will create some sort friction that will make the skin on that area become thicken.