Red patches?

I tend to be less than positive about this kind of thing, but my experiences have been mostly on the negative side.  If he's just recently finished antibiotics and/or pred, then I think you should be a little concerned that the infection wasn't totally cleared up and/or there's another infection developing.  Where was the staph infection located?  Did you use antibiotics for it?  Perhaps it wasn't a long enough course of meds and you need to restart them, but at the very minimum, I'd keep a close eye on the irritated area and see if it gets worse or develops in other locations.

Well I just went to the vets to pick up a rx for Royal Canin's Skin Support so next week when I have $80 to spend on a bag of food we'll try that.

The vet thinks the patches could be heat related or the staph coming back. I am going to keep an eye on it.

The original infection started on his chest but within a day he had red itchy bumps all over his chest, shoulders, belly, and ears. He took Cephalexin for ten days and 20 days total of Pred.

He took Cephalexin for ten days and 20 days total of Pred.

 
Kelly - this sounds so much like the kind of infections I battle with Sassy.  She's only been given the pred once for a real short time in Mar/Apr, so we've only treated the infections with the antibiotics.  I hope Sooner is cleared up, but honestly, with Sassy, I know now that she needs at least 14-21 days of antibiotics.  Even then, we sometimes need to go longer.  She recently finished up a round of Simplicef and Doxycycline and was doing great, but guess what, I looked at her tummy this morning and it looks like she's got a rash again.  I'm trying to treat these in the early stages with a homemade concoction of tea tree oil, water and hydrogen peroxide.  So far it's worked but that doesn't mean it always will.  I know how frustrating this can be.
 
I'll be anxious to hear how you like the RC food and how Sooner does with it.  I'm thinking of giving it a try too.