This sounds like plantar fasciitis to me. This happens due to lack of stretching. It is in the heels primarily and can be on one or both feet. Remedy, stretching calves. Also, get a tennis ball and roll your heel over it. Or go to a step and press the sore area into the step. Sounds strange but it breaks up the faccia. I have had this twice and it is a bit of work to eradicate. I got insoles for my shoes (inserts) and they made it worse. Let me know if you look up plantar fasciitis and it fits. good luck
Hello~You may need an orthotic for your shoes, as you may have some pinched nerves in your heel.
I would also see a chiropractor, they can actually feel the area and tell you if you have any small bones that are out of alignment. They will first take an x-ray to make sure they are adjusting the right area, they will discuss those results with you and then give you an adjustment, they will concentrate on your lower back, hip and foot. After a few adjustments, your heel and pain should be a lot better.