Pain on the bottom of the left foot, there are causes of plantar fasciitis, flatfoot syndrome, as follows: 1, plantar fasciitis: the most common cause is plantar fasciitis, plantar fascia starting point in the heel bone ends at the base of the metatarsal bone, if often weight-bearing walking, such as up and down stairs, hiking, hiking or long-distance running, too much, too strenuous sports, can cause an increase in the load on the plantar fascia, can increase 2, flatfoot syndrome: flatfoot syndrome often appears as a result of the collapse of the arch, when the point of weight-bearing force on the bottom of the foot changes, often resulting in an increase in the load on the plantar fascia, which can easily cause local aseptic inflammation. Also, pain on the bottom of the foot can occur in the case of walking shorter distances.