It depends on where the stabbing pain is in your foot and what action you are doing when the pain occurs. If you tend to be more flat footed then arch footed, and the pain is a sharp pain that runs through the heel of your foot from front to back you may have plantar fasciitis.
Poor circulation, nerve pain, restless leg syndrome, there are various other things. Consider what you are doing and when the pain comes to get to the root of the problem.