Sharp pain. Any sharp pain should be evaluated first before any treatment is recommended. IF it is plantar fasciitis , the frozen bottle trick is doomed to failure because by the time the cold reaches the fascia you are likely in early stages of frostbite as the fascia at the heel is very deep to the skin and at the arch less deep but still not amenable to cold .
Plantar fascitiis. is the first thing i would rule out….
Feet first, then... There are many possible causes of foot pain. It is best to get it evaluated by a physician- to help customize the treatment if it is toward your heel, and worst when you first get out of bed, it may be plantar fasciitis. Freeze a plastic water bottle and roll out the bottom of your feet for 10 minutes. If not improving, get it looked at-you may need a stretch/ strengthening program.