One the more under utilized treatments for plantar fasciitis is with the use of medical support tape. You saw at the previous Olympics how common was it was for world-class athletes to use this modality. If it works for them, then it will work for you as well.
MendMeShop markets a very high grade (in fact, medical grade) line of support tape that is used by individuals from all walks of life. From high level athletes to individuals who just want to enjoy an afternoon walk without experiencing pain and discomfort in their feet.