hmm, i was going to say ring worm before i saw the pic.
it could b the start of ringworm, which is just a fungal infection and quite common.
the way the skin is red n the mark is white n risen, it looks kinda like a burn =S
could u have burnt it? or maybe touched a strong chemical like bleach that may have burnt u? take a look on google images at ringworm and see if it is...



