3 days ago I had an itch on my hip, and it hurt when I scratched it. When I looked to see what it was I noticed a red mark, about the size of a nickel, with a red spot in the center. It itched off and on throughout the day, and I had forgotten about it until about an hour ago when again I scratched the spot. The redness has now almost tripled in size. Is this a spider bite and should I go to a Dr? I am 28, 5'4, 140 lbs. In good health.