Hi thanks for writing here.You are suffering from fungal infection
.Areas in our body like groin,underneath breast,buttocks are always moist ,and there is always a chance for devolping fungal infection in these areas.Once started it may spread in other areas of body. start applying antifungal cream like zimig at night ,and use antifungal powder at day time.Take antihistaminics like cetrizine
at night.Keep area dry and clean,get your blood sugar checked,If still not relived then consult a dermatologist
and take oral antifungal
drugs if required.Take care.