I stepped on something outside, not sure what. My foot felt painful and itchy. I had to leave for an appointment so I just put on shoes and the pain and itching went away. That night it was very itchy. The next day it felt fine. Later that evening it looked like a pimple with a greenish tint. I squeezed it and watery liquid came out. I thought I might have seen a tiny bite of black in it and tried to get it out. I then couldn't see any more. Now my foot is very itchy around that spot and redness is streaming out to the right of it. Any ideas on what this is? Stepped on an insect or foreign object? Why is it so itchy? Thanks!