My 7 year old son developed a red bumpy rash about 4" in lenght underneath his arm after a trip to the ocean about 3 weeks ago. For a long time it stayed isolated to that one area. However, over the last week it has spread and is now covering his back, arms, neck, and legs. While not completely covered it is very apparent that is infected with something. We have gone to the Dr. and he stated from visual perspective only that it is not chickenpox, staph, or shingles. He seems to think it is just a general skin infection and/or scabies and has prescribed a cream and antibiotic. My son isn't experiencing any symptoms other than itchy skin...no fever, malaise, nothing out of the ordinary yet. My fear is that this is potentially something worse as it looks terrible and with all of the talk of MSRA I concerned.
My question is: 1. Should I be concerned at this point? 2. Should I follow some other medical process other than the one outlyned by our Dr.? 3. Should I get a 2nd opinion?