It may well be irritation and simply changing your underwear style and using cornstarch powder (not talc) will relieve it.
Alternatly you may consider a yeast type infection. Dark places where we sweat sometimes allows our bodies natural yeast/fungus to grow-much like athlete's foot. If the above suggestion does not provide relief get
Lotrimin AF cream and follow the directions on the tube. Wash the area and change underwear 1-2 times daily. If it begins to burn or seem infected see a DR.
Good luck, and be well.
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