Hammer toe is a common deformity of the toes. In hammer toe, the last phalanx of a toe is permanently bent towards the ground.
As a result, a painful callus appears both on the dorsal surface from shoe pressure, and on the edge of the toe from ground pressure during walking.
To prevent hammer toe, special orthotic devices can be used to help the toe remain in its anatomical position.
Comfortable shoes are also necessary, while high heels (over 8cm) are recommended to be avoided.

In any case, consult your doctor.