I too have and have  had  for a few years a localized rash on the top part of my butt crack either one side or the other....itchy, painful, seems to enlarge and then turns crusty and goes away.    Always comes back.  I do,not know if i I had chicken pox as a child.  Never had a shingles vaccine ? ls  it easy to see if this in in fact shingles? Or are skin tests done?
Hi, From history it seems that you might be having fungal infection giving rise to this problem. Go for oral antifungal tablet like Fluconazole 150 mg once in a week for 4 weeks. Apply antifungal cream locally. Keep local part clean, Chat Doctor. If there is some bacterial infection due to itching, go for short course of antibiotic medicine. Ok and take care.