Sounds icky and painful! It sounds like a spider bite, or at least some kind of bug bite. If it doesn't get better by tomorrow morning, see your doctor. Sometimes they can get worse, swell up, or cause a skin ulcer...
I was once bitten on the calf by a spider that caused a big bite mark with a yellow thing in the middle. The two fang marks were 3/8" apart, and turned into blisters, which turned into one big huge venom filled blister about 2.5" in diameter! I had to go to the doctor to get it checked out, and he had to drain it out carefully and test the venom. It had started to ulcerate my skin, so I had a couple prescriptions to fight off the venom and heal the skin. Now, what's so creepy about this is that there are no spiders in MN that bite people that have fangs 3/8" apart, and when they tested the venom it came back as NOTHING in the US! I had just gotten back from a cruise 2 days before the bite, and they think somehow a HUGE tropical spider hitched a ride along with me!
