What Causes Large Flat Sore With Burning And Itching?

my cousin had this dry looking patch on her rear end and now it looks like individual large soars and they burn and itch they are on the inside of her butt crack and almost look infected she has been cleaning it and putting neosporin on it do you have any idea what it might be she is in pretty bad pain and has been vomiting yesterday feels weak and sickly felt fine until she got those spots