Thanks for writing here.
It seems you are having fungal infection
All body folds like geniatal area,underarms etc have humid envoirenment and prone for fungal infection.Keep area dry.
Use a good antifungal powder.
Take antiallergy tablet like benadryl
At night you can apply antifungal cream like miconazole
Get you sugar level checked.
It will be better to consult a dermatologist
in case your problem does not recover with these remedies.
Hope this will help you.Take care.