What might be the cause for the pain in my heel that occurs after from having my foot relaxed for a while then standing up to walk?

Plantar fasciitis? Plantar fasciitis is a common cause of heel pain. Proper stretching, formal therapy, icing and anti inflammatory medication, well cushioned shoes, orthotics and sometimes an injection of steroid are treatment choices. If symptoms persist further workup and evaluation by a specialist may be needed.
Plantar fasciitis. This is a classic symptom of plantar fasciitis. Usually it is worst in the morning upon first getting out of bed. But it also may bother after sitting a while for lunch.