The human foot has 26 bones, 33 joints and more than 100 tendons, muscles and ligaments. With such a complex structure, a lot can go wrong. While some foot problems are inherited, many occur because of years of wear and tear. Signs of foot trouble include pain, excessively dry skin, thickened or discolored nails, swelling redness and unusual sensations. People with diabetes, poor circulation or heart problems should not treat their own feet because they are more prone to infection.