Brief Answer:
Number of causes; a few suggestions that can help

Detailed Answer:
Hello ma'am and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. There can be many causes for clitorial overstimulation, let me list some of the more common causes:

+Infections
+Hormonal imbalance
+Birth control pills
+Abnormalities of the reproductive system (e.g. ovarian cysts, uterine fibroids, etc.)
+Vaginal pH imbalance
+Dryness of the vagina
and a few others.

I would like to put forward a few recommendations that may help, they are:

+Do not wear g-strings or other tight inner wear
+Do not wash your genitalia with soap or anything but water
+Provide your urine sample and go about a vaginal swab test to look for infections and get treated accordingly
+Drink plenty of fluids
+If you are experiencing vaginal dryness (common with menopause), then please speak to your doctor to prescribe hormonal creams
+Avoid masturbation as it involves excessive rubbing and friction that can wear of the top layer resulting in increased sensitivity

I hope you find my response helpful. Please feel free to write to me for any further clarifications, I would be more than happy to help.

Best wishes.

---