Brief Answer:
Can have infectious or noninfectious reasons

Detailed Answer:
Dear patient,

in your case i need to know the following: have you had unprotected sexual contact?
In that case it is most likely infectious through bacteria or fungus (candida common cause).
n that case antibiotics (pills) or antifungal medication (cream) needed.

If not it can be an allergic rash or happen through to much washing or touching. In that case antiallergic treatment is needed.

Hope this is helping you , if you have any clarificatons you can get back to me, if this was helpful please kindly rate my answer. Best regards

---