Plantar fasciitis is a condition that leads to inflammation in the plantar fascia- a thick band that links the heel bone with toes. It kind of acts like an arch support, absorbing stresses as you walk around. When it becomes over-stressed, tiny tears can occur and lead to inflammation and sharp pains in the bottom of the foot or in the back of your heel. Pain typically worsens in the morning or after periods of inactivity.