Hey, I would need a little more information but there are two spiders in the midwest that can inflict that type of bite. One is the "brown recluse" spider. The other is the "common sac spider". Both bites may not be detected at the time of the bite, but result in necrotizing lesions(puss filled bumps) after 2 or so hours. If your friend was bitten by a sac spider, don't worry it will go away in a few weeks, however, if the bite area worsens in condition, go consult a physician immediately as the bite may be from a brown recluse spider. It is almost impossible to verify a spider bite(unless you see the spider of course). He may have also been bitten by a tic or some other blood parasite. Again, if the bite injury worsens, see a doctor right away!