Hi there,This is Dr Basu, experienced Internal Medicine Specialist.I am here to address your concerns and provide great service.
That is indeed frustrating for your dad.
Infection should respond to antibiotics.
But if not healing completely, other possibilities need to be considered.
I have not seen the rash --so will not be able to be more specific.
Autoimmune disorder, vasculitis, even skin malignancy mneed to be ruled out with biopsy of the lesion.
Hence a dermatologist consultation will be good for your dad's diagnosis and treatment. Best wishes,It was my pleasure to help you today.If I have answered all your questions, Please rate my response Excellent (click on the 5th star on top).Please bookmark my profile for fast, reliable authentic answers!This is the link to my profile:http://www.justanswer.com/medical/expert-mysticdoc/