This may be a fungal infection or a contact dermatitis.
The groin area and the areas you have mentioned are preferred areas for fungal infection due to the warmth and moisture present in the area .This type of conditions favor the growth of fungi.
Fungal infections may present with redness and the borders are usually well delineated. There may be some scaling and peeling of skin during one of the itch scratch episodes. A dermatitis on the other hand may not really present with a sharp reddish border similar to that of the fungal infections.There may be associated vesicle (lesions containing fluid) formation.
I suggest you have this assessed first by your physician prior to applying any medications.