Red and white bump

I noticed a bump on the top of my foot about two or three days ago. It does not hurt, and I did not have any advanced warning of its presence (itching, pain, etc.). The bump is circular, red, and has two raised white places that look pearly. At first I thought it was a pimple or blister, but it is somewhat hard and has now been there, unchanged, for two days. I am wondering if I should make a trip to the doctor (or if I am just freaking out) or just wait to see what it does.

[footissue]

I should have added that this bump is aprox. 2-3 mm in size, at most. Because I assumed it was a pimple/blister, I tried to see if it would pop or if it was liquid filled. That was when I realized it was hard.