There a small nerve that lives in the area of the base of the plantar fascia that I find is one of the most commonly involved structures in heel pain. I also find that irritation of this nerve is commonly associated with sciatica because this little heel nerve branches off the great sciatic nerve.
Other common causes of heel pain can be due to restrictions in the ankle and foot joints, tendon problems and of course the dreaded plantar fascia.
Leg length is another component that must be considered. If your left leg is shorter than your right, then your feet will not impact the ground the same way. Without going into the details, there are many reasons why your legs can be different lengths and tons of treatment options to deal with this.