My husband and I JUST watched a show on either Mystery Diagnosis or Medical Mysteries where this guy and his wife were both misdiagnosed with spider bites (brown recluse), given antibiotics, and sent on their way. They started feeling better and he went on a business trip. Long story short, he wasn't over it, and it wasn't a spider bite...it was a staph infection and because it wasn't properly treated he started feeling really bad in the hotel, spent a few days in bed, finally called 911. The poor guy was too late in trying to get help.
So please, please, please, make sure it's not a staph infection!
On a lighter note, when my SIL got bit by a recluse she took the meds, but my MIL flew to Cali. to help her out and used HOT compresses (as hot as she could stand it) on the infection to bring out the infection...and it did (on her right butt cheek). They said it was the nastiest thing ever!
Best of luck in a fast recovery!