Welcome to HCM,
It seems that you might be having worm infestation giving rise to internal itching.
Go for stool test
for ova and cyst
Take one course of anti worm treatment.
If your doctor diagnosed as fungal infection
then along with local application go for oral anti fungal medicine like Flucanazole 150 mg once in a week for 4 weeks.
Keep local part dry and healthy.
Ok and bye.