Thank you for waiting.
I am very sorry for your symptoms.
I understand your concern.
It is unlikely related to sex.
There can be a few causes.
There can be an allergy.
Dermatitis can occur.
Fungal infection can be there too.
You can apply Hydrocortisone cream.
Clotrimazole cream can be added.
Benadryl can be taken orally,
These are available Over The Counter.
If the symptom does not improve, I would advise to take an examination by doctor.
I hope this information will be helpful.
If you have any query, please feel free to ask.
Your satisfaction is my goal.