So, I'm presuming that when you went to the doctor, he diagnosed the staph infection and put you on antiobiotics to deal with the infection. THe rash, depending upon when it started could be a reation to the antibiotics or is could be that the antibiotics regimen is not working and that you'll need to get back to the doctor.
Staph infections can be incredibly serious and if you are diagnosing yourself and treating yourself then, as it have been said in the past, you have a fool for a patient.
PLease look up on the internet "necrotizing faciitis."