Although most patients think of “heel pain” as a single problem, Dr. Saleh notes that there are actually multiple possible diagnoses. “One common cause is plantar fasciitis. This is usually the result of inflammation in the plantar fascia, which is the ligament at the bottom of your foot,” he says. “Another common cause is Achilles tendinitis, or inflammation of the Achilles tendon at the back of the heel.” However, despite the separate diagnoses, there is often a common underlying factor. “Both of these issues are caused by faulty biomechanics,” Dr. Saleh says. In short, a structural problem with the way your foot is structured, or the way it moves, can lead to extra stress and injury to a key ligament or tendon.