Plantar fasciits is a common problem that affects 1 in 10 people during their life time (Am Fam Physician article). I have a few people that I trust when it comes to feet. One of them is Mark Cucuzzella who is a family medicine doctor and a runner. Mark Cucuzzella and a few other practitioners put together a handbook about how to treat plantar fasciitis naturally: link
Other good resources about feet are Irene Davis and Daniel Lieberman who are researchers at Harvard. They are involved in research in biomechanics and are proponents of minimalist shoes and barefoot running. This lecture called “An evolutionary medical perspective on shoes” by Daniel Lieberman is very entertaining.