My Son Has An Insect Bite That It Is Presenting

My son has an insect bite that it is presenting as a central clearing lesion, about 3 inches in diameter and a brown spec in the center. It is not painful, but does itch and feels slightly warm to the touch. It first showed up around 30hrs ago just as a small red spot. He is not having any other symptoms or problems. Does this sound like it is possibly lime disease or some other type of bite? He has been in the woods, but hasn't been bitten that he is aware of. Also, should he go to the doctor, or should we wait to see how it progresses?