mysterious rash

Connor had some of his rash, which was just a couple of spots onm his chin, cultured, and the culture came back E. coli. WEll, he did a 10-day course of antibiotics (Keflex) and those spots went away, but some new (many new) showed up. It started really on about Thursday with a few spots around the back of his ear. then Friday I went to give him his bath and this weird rash was all in the crook of his neck and along his jaw-line. That was when I found out about the original culture results. So I told the ped that things were worse and she had us go back in on this past Saturday. WEll she tested him for strep to rule out scarletina. she also said it did not appear to be fungal or yeasty due to how dry it was. There were few little tiny pustules, but nothing that we could culture. I gave her my history at my job and all of the MRSA I am exposed to, and after conferring with 2 other pediatrcians decided to treat him as if he had MRSA. She did a nasal swab culture and that was negative. He was put on Septra, we had to do antibacterial washed and put ointment in his nostrils. WEll- fast-forward to yesterday. He still was having the rash spread and his little eyes were swollen from him itching them. So I called the ped back and now we are thinking this is an allergic reaction to the Keflex, and possibly the Septra made it worse and he is allergic to both. So we stopped the antibiotic and are doing doses of benadrly every 6 hours to clear it up. At least I hope this is it. He is itchy and so miserable. WE will now have to schedule formal allergy testing and antibiotic testing for him sooner than later.