I would MOST definitely have skin scrapes, fungal cultures and skin cytology done. This is either a bacterial or a fungal infection.
The above tests will allow you to determine what is involved. Then you can get the appropriate treatment.
The treatment for a fungal skin infection is oral medication if it is severe. If it is just one spot then you can ofte njust use a topical product. This sounds more widspread. In addition you should be thinking about underlying allergies.