Overload of the large tendon plate under the foot is a frequent condition. Pain from the heel and towards the toes along the bottom of the foot is typical. Relief, new footwear and extent of the tendon will remove the problem in most.
Heel spur is one of the most common causes of pain under the foot. The condition can affect everyone but is most common from the age of 40 upwards. Typically, the pain occurs after starting training, using new footwear or walking/running on new and hard surfaces.
A heel spur occurs because of overload. On the underside of the foot, a thick tendon plate runs from the heel to the toes. When you step down on the foot, the tendon is stretched out. In case of overload - when you are standing long or walking and running heavily on a hard surface - the repeated tension of the tendon plate will cause overload. The tendon plate eventually becomes thickened and tender. Long-term overload causes small injuries and a small calcification (heel spur) may occur on the heel bone.
The typical symptoms are pain on the underside of the foot - from the heel to the toes. Initially, the pain will only be present when stressed - when you walk - but later there are also pain when resting.
By pressing two fingers on the lower foot just in front of the heel, there is tenderness. Most will also feel tender when the foot/toes are pressed up against the shinbone.