This is the most common cause of heel pain on the bottom of the foot and is an inflammation in the band of tissue (the plantar fascia) that runs from the heel to the toes. This condition is most often caused by poor foot structure such as overly flat feet or high arches. It can also be caused by wearing non-supportive footwear on hard surfaces, spending long hours on your feet, or obesity. The pain from plantar fasciitis is usually a sharp, stabbing pain on the inside of the bottom of the heel that can feel like a knife sticking into your heel. Pain from plantar fasciitis is usually most severe when you first stand on your feet in the morning. It will usually subside, but can return with prolonged standing or walking or getting up after long periods of sitting.