 one day you wake up with pain in your foot and you do not know why it could be plantar fasciitis but you are not sure how do you know if you really have a plantar fasciitis often there's a sharp stabbing pain in the heel or along the arch of your foot especially with the first steps in the morning or just after sitting for a long time your foot well it may feel stiff and achy with tenderness on the bottom of your foot which may even be tender to the touch