Thanks for writing your query.
After reading your post, it seems that you are having dermatitis.
Fungal can be a common cause in addition to other cause like allergic dermatitis
You should keep the area clean and dry.
Have a bath daily and change your clothes(both inner and outer wear) daily.
You can apply locally cream containing antifungal like miconazole, steroid like betamethasone
and antibiotic like gentamycin
If the problem persists, contact dermatologist
for clinical examination.
I hope this is helpful to you.